1 ================ 1 ================
2 Event Histograms 2 Event Histograms
3 ================ 3 ================
4 4
5 Documentation written by Tom Zanussi 5 Documentation written by Tom Zanussi
6 6
7 1. Introduction 7 1. Introduction
8 =============== 8 ===============
9 9
10 Histogram triggers are special event trigger 10 Histogram triggers are special event triggers that can be used to
11 aggregate trace event data into histograms. 11 aggregate trace event data into histograms. For information on
12 trace events and event triggers, see Documen 12 trace events and event triggers, see Documentation/trace/events.rst.
13 13
14 14
15 2. Histogram Trigger Command 15 2. Histogram Trigger Command
16 ============================ 16 ============================
17 17
18 A histogram trigger command is an event trig 18 A histogram trigger command is an event trigger command that
19 aggregates event hits into a hash table keye 19 aggregates event hits into a hash table keyed on one or more trace
20 event format fields (or stacktrace) and a se 20 event format fields (or stacktrace) and a set of running totals
21 derived from one or more trace event format 21 derived from one or more trace event format fields and/or event
22 counts (hitcount). 22 counts (hitcount).
23 23
24 The format of a hist trigger is as follows:: 24 The format of a hist trigger is as follows::
25 25
26 hist:keys=<field1[,field2,...]>[:value 26 hist:keys=<field1[,field2,...]>[:values=<field1[,field2,...]>]
27 [:sort=<field1[,field2,...]>][:size= 27 [:sort=<field1[,field2,...]>][:size=#entries][:pause][:continue]
28 [:clear][:name=histname1][:nohitcoun 28 [:clear][:name=histname1][:nohitcount][:<handler>.<action>] [if <filter>]
29 29
30 When a matching event is hit, an entry is ad 30 When a matching event is hit, an entry is added to a hash table
31 using the key(s) and value(s) named. Keys a 31 using the key(s) and value(s) named. Keys and values correspond to
32 fields in the event's format description. V 32 fields in the event's format description. Values must correspond to
33 numeric fields - on an event hit, the value( 33 numeric fields - on an event hit, the value(s) will be added to a
34 sum kept for that field. The special string 34 sum kept for that field. The special string 'hitcount' can be used
35 in place of an explicit value field - this i 35 in place of an explicit value field - this is simply a count of
36 event hits. If 'values' isn't specified, an 36 event hits. If 'values' isn't specified, an implicit 'hitcount'
37 value will be automatically created and used 37 value will be automatically created and used as the only value.
38 Keys can be any field, or the special string !! 38 Keys can be any field, or the special string 'stacktrace', which
39 will use the event's kernel stacktrace as th 39 will use the event's kernel stacktrace as the key. The keywords
40 'keys' or 'key' can be used to specify keys, 40 'keys' or 'key' can be used to specify keys, and the keywords
41 'values', 'vals', or 'val' can be used to sp 41 'values', 'vals', or 'val' can be used to specify values. Compound
42 keys consisting of up to three fields can be 42 keys consisting of up to three fields can be specified by the 'keys'
43 keyword. Hashing a compound key produces a 43 keyword. Hashing a compound key produces a unique entry in the
44 table for each unique combination of compone 44 table for each unique combination of component keys, and can be
45 useful for providing more fine-grained summa 45 useful for providing more fine-grained summaries of event data.
46 Additionally, sort keys consisting of up to 46 Additionally, sort keys consisting of up to two fields can be
47 specified by the 'sort' keyword. If more th 47 specified by the 'sort' keyword. If more than one field is
48 specified, the result will be a 'sort within 48 specified, the result will be a 'sort within a sort': the first key
49 is taken to be the primary sort key and the 49 is taken to be the primary sort key and the second the secondary
50 key. If a hist trigger is given a name usin 50 key. If a hist trigger is given a name using the 'name' parameter,
51 its histogram data will be shared with other 51 its histogram data will be shared with other triggers of the same
52 name, and trigger hits will update this comm 52 name, and trigger hits will update this common data. Only triggers
53 with 'compatible' fields can be combined in 53 with 'compatible' fields can be combined in this way; triggers are
54 'compatible' if the fields named in the trig 54 'compatible' if the fields named in the trigger share the same
55 number and type of fields and those fields a 55 number and type of fields and those fields also have the same names.
56 Note that any two events always share the co 56 Note that any two events always share the compatible 'hitcount' and
57 'common_stacktrace' fields and can therefore !! 57 'stacktrace' fields and can therefore be combined using those
58 fields, however pointless that may be. 58 fields, however pointless that may be.
59 59
60 'hist' triggers add a 'hist' file to each ev 60 'hist' triggers add a 'hist' file to each event's subdirectory.
61 Reading the 'hist' file for the event will d 61 Reading the 'hist' file for the event will dump the hash table in
62 its entirety to stdout. If there are multip 62 its entirety to stdout. If there are multiple hist triggers
63 attached to an event, there will be a table 63 attached to an event, there will be a table for each trigger in the
64 output. The table displayed for a named tri 64 output. The table displayed for a named trigger will be the same as
65 any other instance having the same name. Eac 65 any other instance having the same name. Each printed hash table
66 entry is a simple list of the keys and value 66 entry is a simple list of the keys and values comprising the entry;
67 keys are printed first and are delineated by 67 keys are printed first and are delineated by curly braces, and are
68 followed by the set of value fields for the 68 followed by the set of value fields for the entry. By default,
69 numeric fields are displayed as base-10 inte 69 numeric fields are displayed as base-10 integers. This can be
70 modified by appending any of the following m 70 modified by appending any of the following modifiers to the field
71 name: 71 name:
72 72
73 ============= ======================= 73 ============= =================================================
74 .hex display a number as a h 74 .hex display a number as a hex value
75 .sym display an address as a 75 .sym display an address as a symbol
76 .sym-offset display an address as a 76 .sym-offset display an address as a symbol and offset
77 .syscall display a syscall id as 77 .syscall display a syscall id as a system call name
78 .execname display a common_pid as 78 .execname display a common_pid as a program name
79 .log2 display log2 value rath 79 .log2 display log2 value rather than raw number
80 .buckets=size display grouping of val 80 .buckets=size display grouping of values rather than raw number
81 .usecs display a common_timest 81 .usecs display a common_timestamp in microseconds
82 .percent display a number of per 82 .percent display a number of percentage value
83 .graph display a bar-graph of 83 .graph display a bar-graph of a value
84 .stacktrace display as a stacktrace <<
85 ============= ======================= 84 ============= =================================================
86 85
87 Note that in general the semantics of a give 86 Note that in general the semantics of a given field aren't
88 interpreted when applying a modifier to it, 87 interpreted when applying a modifier to it, but there are some
89 restrictions to be aware of in this regard: 88 restrictions to be aware of in this regard:
90 89
91 - only the 'hex' modifier can be used for 90 - only the 'hex' modifier can be used for values (because values
92 are essentially sums, and the other modi 91 are essentially sums, and the other modifiers don't make sense
93 in that context). 92 in that context).
94 - the 'execname' modifier can only be used 93 - the 'execname' modifier can only be used on a 'common_pid'. The
95 reason for this is that the execname is 94 reason for this is that the execname is simply the 'comm' value
96 saved for the 'current' process when an 95 saved for the 'current' process when an event was triggered,
97 which is the same as the common_pid valu 96 which is the same as the common_pid value saved by the event
98 tracing code. Trying to apply that comm 97 tracing code. Trying to apply that comm value to other pid
99 values wouldn't be correct, and typicall 98 values wouldn't be correct, and typically events that care save
100 pid-specific comm fields in the event it 99 pid-specific comm fields in the event itself.
101 100
102 A typical usage scenario would be the follow 101 A typical usage scenario would be the following to enable a hist
103 trigger, read its current contents, and then 102 trigger, read its current contents, and then turn it off::
104 103
105 # echo 'hist:keys=skbaddr.hex:vals=len' > 104 # echo 'hist:keys=skbaddr.hex:vals=len' > \
106 /sys/kernel/tracing/events/net/netif_rx/ !! 105 /sys/kernel/debug/tracing/events/net/netif_rx/trigger
107 106
108 # cat /sys/kernel/tracing/events/net/netif !! 107 # cat /sys/kernel/debug/tracing/events/net/netif_rx/hist
109 108
110 # echo '!hist:keys=skbaddr.hex:vals=len' > 109 # echo '!hist:keys=skbaddr.hex:vals=len' > \
111 /sys/kernel/tracing/events/net/netif_rx/ !! 110 /sys/kernel/debug/tracing/events/net/netif_rx/trigger
112 111
113 The trigger file itself can be read to show 112 The trigger file itself can be read to show the details of the
114 currently attached hist trigger. This infor 113 currently attached hist trigger. This information is also displayed
115 at the top of the 'hist' file when read. 114 at the top of the 'hist' file when read.
116 115
117 By default, the size of the hash table is 20 116 By default, the size of the hash table is 2048 entries. The 'size'
118 parameter can be used to specify more or few 117 parameter can be used to specify more or fewer than that. The units
119 are in terms of hashtable entries - if a run 118 are in terms of hashtable entries - if a run uses more entries than
120 specified, the results will show the number 119 specified, the results will show the number of 'drops', the number
121 of hits that were ignored. The size should 120 of hits that were ignored. The size should be a power of 2 between
122 128 and 131072 (any non- power-of-2 number s 121 128 and 131072 (any non- power-of-2 number specified will be rounded
123 up). 122 up).
124 123
125 The 'sort' parameter can be used to specify 124 The 'sort' parameter can be used to specify a value field to sort
126 on. The default if unspecified is 'hitcount 125 on. The default if unspecified is 'hitcount' and the default sort
127 order is 'ascending'. To sort in the opposi 126 order is 'ascending'. To sort in the opposite direction, append
128 .descending' to the sort key. 127 .descending' to the sort key.
129 128
130 The 'pause' parameter can be used to pause a 129 The 'pause' parameter can be used to pause an existing hist trigger
131 or to start a hist trigger but not log any e 130 or to start a hist trigger but not log any events until told to do
132 so. 'continue' or 'cont' can be used to sta 131 so. 'continue' or 'cont' can be used to start or restart a paused
133 hist trigger. 132 hist trigger.
134 133
135 The 'clear' parameter will clear the content 134 The 'clear' parameter will clear the contents of a running hist
136 trigger and leave its current paused/active 135 trigger and leave its current paused/active state.
137 136
138 Note that the 'pause', 'cont', and 'clear' p 137 Note that the 'pause', 'cont', and 'clear' parameters should be
139 applied using 'append' shell operator ('>>') 138 applied using 'append' shell operator ('>>') if applied to an
140 existing trigger, rather than via the '>' op 139 existing trigger, rather than via the '>' operator, which will cause
141 the trigger to be removed through truncation 140 the trigger to be removed through truncation.
142 141
143 The 'nohitcount' (or NOHC) parameter will su 142 The 'nohitcount' (or NOHC) parameter will suppress display of
144 raw hitcount in the histogram. This option r 143 raw hitcount in the histogram. This option requires at least one
145 value field which is not a 'raw hitcount'. F 144 value field which is not a 'raw hitcount'. For example,
146 'hist:...:vals=hitcount:nohitcount' is rejec 145 'hist:...:vals=hitcount:nohitcount' is rejected, but
147 'hist:...:vals=hitcount.percent:nohitcount' 146 'hist:...:vals=hitcount.percent:nohitcount' is OK.
148 147
149 - enable_hist/disable_hist 148 - enable_hist/disable_hist
150 149
151 The enable_hist and disable_hist triggers ca 150 The enable_hist and disable_hist triggers can be used to have one
152 event conditionally start and stop another e 151 event conditionally start and stop another event's already-attached
153 hist trigger. Any number of enable_hist and 152 hist trigger. Any number of enable_hist and disable_hist triggers
154 can be attached to a given event, allowing t 153 can be attached to a given event, allowing that event to kick off
155 and stop aggregations on a host of other eve 154 and stop aggregations on a host of other events.
156 155
157 The format is very similar to the enable/dis 156 The format is very similar to the enable/disable_event triggers::
158 157
159 enable_hist:<system>:<event>[:count] 158 enable_hist:<system>:<event>[:count]
160 disable_hist:<system>:<event>[:count] 159 disable_hist:<system>:<event>[:count]
161 160
162 Instead of enabling or disabling the tracing 161 Instead of enabling or disabling the tracing of the target event
163 into the trace buffer as the enable/disable_ 162 into the trace buffer as the enable/disable_event triggers do, the
164 enable/disable_hist triggers enable or disab 163 enable/disable_hist triggers enable or disable the aggregation of
165 the target event into a hash table. 164 the target event into a hash table.
166 165
167 A typical usage scenario for the enable_hist 166 A typical usage scenario for the enable_hist/disable_hist triggers
168 would be to first set up a paused hist trigg 167 would be to first set up a paused hist trigger on some event,
169 followed by an enable_hist/disable_hist pair 168 followed by an enable_hist/disable_hist pair that turns the hist
170 aggregation on and off when conditions of in 169 aggregation on and off when conditions of interest are hit::
171 170
172 # echo 'hist:keys=skbaddr.hex:vals=len:paus 171 # echo 'hist:keys=skbaddr.hex:vals=len:pause' > \
173 /sys/kernel/tracing/events/net/netif_rec !! 172 /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger
174 173
175 # echo 'enable_hist:net:netif_receive_skb 174 # echo 'enable_hist:net:netif_receive_skb if filename==/usr/bin/wget' > \
176 /sys/kernel/tracing/events/sched/sched_p !! 175 /sys/kernel/debug/tracing/events/sched/sched_process_exec/trigger
177 176
178 # echo 'disable_hist:net:netif_receive_skb 177 # echo 'disable_hist:net:netif_receive_skb if comm==wget' > \
179 /sys/kernel/tracing/events/sched/sched_p !! 178 /sys/kernel/debug/tracing/events/sched/sched_process_exit/trigger
180 179
181 The above sets up an initially paused hist t 180 The above sets up an initially paused hist trigger which is unpaused
182 and starts aggregating events when a given p 181 and starts aggregating events when a given program is executed, and
183 which stops aggregating when the process exi 182 which stops aggregating when the process exits and the hist trigger
184 is paused again. 183 is paused again.
185 184
186 The examples below provide a more concrete i 185 The examples below provide a more concrete illustration of the
187 concepts and typical usage patterns discusse 186 concepts and typical usage patterns discussed above.
188 187
189 'special' event fields 188 'special' event fields
190 ------------------------ 189 ------------------------
191 190
192 There are a number of 'special event fields' 191 There are a number of 'special event fields' available for use as
193 keys or values in a hist trigger. These loo 192 keys or values in a hist trigger. These look like and behave as if
194 they were actual event fields, but aren't re 193 they were actual event fields, but aren't really part of the event's
195 field definition or format file. They are h 194 field definition or format file. They are however available for any
196 event, and can be used anywhere an actual ev 195 event, and can be used anywhere an actual event field could be.
197 They are: 196 They are:
198 197
199 ====================== ==== ============== 198 ====================== ==== =======================================
200 common_timestamp u64 timestamp (fro 199 common_timestamp u64 timestamp (from ring buffer) associated
201 with the event 200 with the event, in nanoseconds. May be
202 modified by .u 201 modified by .usecs to have timestamps
203 interpreted as 202 interpreted as microseconds.
204 common_cpu int the cpu on whi 203 common_cpu int the cpu on which the event occurred.
205 ====================== ==== ============== 204 ====================== ==== =======================================
206 205
207 Extended error information 206 Extended error information
208 -------------------------- 207 --------------------------
209 208
210 For some error conditions encountered when i 209 For some error conditions encountered when invoking a hist trigger
211 command, extended error information is avail 210 command, extended error information is available via the
212 tracing/error_log file. See Error Condition 211 tracing/error_log file. See Error Conditions in
213 :file:`Documentation/trace/ftrace.rst` for d 212 :file:`Documentation/trace/ftrace.rst` for details.
214 213
215 6.2 'hist' trigger examples 214 6.2 'hist' trigger examples
216 --------------------------- 215 ---------------------------
217 216
218 The first set of examples creates aggregatio 217 The first set of examples creates aggregations using the kmalloc
219 event. The fields that can be used for the 218 event. The fields that can be used for the hist trigger are listed
220 in the kmalloc event's format file:: 219 in the kmalloc event's format file::
221 220
222 # cat /sys/kernel/tracing/events/kmem/kmal !! 221 # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/format
223 name: kmalloc 222 name: kmalloc
224 ID: 374 223 ID: 374
225 format: 224 format:
226 field:unsigned short common_type; 225 field:unsigned short common_type; offset:0; size:2; signed:0;
227 field:unsigned char common_flags; 226 field:unsigned char common_flags; offset:2; size:1; signed:0;
228 field:unsigned char common_preempt_cou 227 field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
229 field:int common_pid; 228 field:int common_pid; offset:4; size:4; signed:1;
230 229
231 field:unsigned long call_site; 230 field:unsigned long call_site; offset:8; size:8; signed:0;
232 field:const void * ptr; 231 field:const void * ptr; offset:16; size:8; signed:0;
233 field:size_t bytes_req; 232 field:size_t bytes_req; offset:24; size:8; signed:0;
234 field:size_t bytes_alloc; 233 field:size_t bytes_alloc; offset:32; size:8; signed:0;
235 field:gfp_t gfp_flags; 234 field:gfp_t gfp_flags; offset:40; size:4; signed:0;
236 235
237 We'll start by creating a hist trigger that 236 We'll start by creating a hist trigger that generates a simple table
238 that lists the total number of bytes request 237 that lists the total number of bytes requested for each function in
239 the kernel that made one or more calls to km 238 the kernel that made one or more calls to kmalloc::
240 239
241 # echo 'hist:key=call_site:val=bytes_req.b 240 # echo 'hist:key=call_site:val=bytes_req.buckets=32' > \
242 /sys/kernel/tracing/events/kmem/km !! 241 /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
243 242
244 This tells the tracing system to create a 'h 243 This tells the tracing system to create a 'hist' trigger using the
245 call_site field of the kmalloc event as the 244 call_site field of the kmalloc event as the key for the table, which
246 just means that each unique call_site addres 245 just means that each unique call_site address will have an entry
247 created for it in the table. The 'val=bytes 246 created for it in the table. The 'val=bytes_req' parameter tells
248 the hist trigger that for each unique entry 247 the hist trigger that for each unique entry (call_site) in the
249 table, it should keep a running total of the 248 table, it should keep a running total of the number of bytes
250 requested by that call_site. 249 requested by that call_site.
251 250
252 We'll let it run for awhile and then dump th 251 We'll let it run for awhile and then dump the contents of the 'hist'
253 file in the kmalloc event's subdirectory (fo 252 file in the kmalloc event's subdirectory (for readability, a number
254 of entries have been omitted):: 253 of entries have been omitted)::
255 254
256 # cat /sys/kernel/tracing/events/kmem/kmal !! 255 # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist
257 # trigger info: hist:keys=call_site:vals=b 256 # trigger info: hist:keys=call_site:vals=bytes_req:sort=hitcount:size=2048 [active]
258 257
259 { call_site: 18446744072106379007 } hitcou 258 { call_site: 18446744072106379007 } hitcount: 1 bytes_req: 176
260 { call_site: 18446744071579557049 } hitcou 259 { call_site: 18446744071579557049 } hitcount: 1 bytes_req: 1024
261 { call_site: 18446744071580608289 } hitcou 260 { call_site: 18446744071580608289 } hitcount: 1 bytes_req: 16384
262 { call_site: 18446744071581827654 } hitcou 261 { call_site: 18446744071581827654 } hitcount: 1 bytes_req: 24
263 { call_site: 18446744071580700980 } hitcou 262 { call_site: 18446744071580700980 } hitcount: 1 bytes_req: 8
264 { call_site: 18446744071579359876 } hitcou 263 { call_site: 18446744071579359876 } hitcount: 1 bytes_req: 152
265 { call_site: 18446744071580795365 } hitcou 264 { call_site: 18446744071580795365 } hitcount: 3 bytes_req: 144
266 { call_site: 18446744071581303129 } hitcou 265 { call_site: 18446744071581303129 } hitcount: 3 bytes_req: 144
267 { call_site: 18446744071580713234 } hitcou 266 { call_site: 18446744071580713234 } hitcount: 4 bytes_req: 2560
268 { call_site: 18446744071580933750 } hitcou 267 { call_site: 18446744071580933750 } hitcount: 4 bytes_req: 736
269 . 268 .
270 . 269 .
271 . 270 .
272 { call_site: 18446744072106047046 } hitcou 271 { call_site: 18446744072106047046 } hitcount: 69 bytes_req: 5576
273 { call_site: 18446744071582116407 } hitcou 272 { call_site: 18446744071582116407 } hitcount: 73 bytes_req: 2336
274 { call_site: 18446744072106054684 } hitcou 273 { call_site: 18446744072106054684 } hitcount: 136 bytes_req: 140504
275 { call_site: 18446744072106224230 } hitcou 274 { call_site: 18446744072106224230 } hitcount: 136 bytes_req: 19584
276 { call_site: 18446744072106078074 } hitcou 275 { call_site: 18446744072106078074 } hitcount: 153 bytes_req: 2448
277 { call_site: 18446744072106062406 } hitcou 276 { call_site: 18446744072106062406 } hitcount: 153 bytes_req: 36720
278 { call_site: 18446744071582507929 } hitcou 277 { call_site: 18446744071582507929 } hitcount: 153 bytes_req: 37088
279 { call_site: 18446744072102520590 } hitcou 278 { call_site: 18446744072102520590 } hitcount: 273 bytes_req: 10920
280 { call_site: 18446744071582143559 } hitcou 279 { call_site: 18446744071582143559 } hitcount: 358 bytes_req: 716
281 { call_site: 18446744072106465852 } hitcou 280 { call_site: 18446744072106465852 } hitcount: 417 bytes_req: 56712
282 { call_site: 18446744072102523378 } hitcou 281 { call_site: 18446744072102523378 } hitcount: 485 bytes_req: 27160
283 { call_site: 18446744072099568646 } hitcou 282 { call_site: 18446744072099568646 } hitcount: 1676 bytes_req: 33520
284 283
285 Totals: 284 Totals:
286 Hits: 4610 285 Hits: 4610
287 Entries: 45 286 Entries: 45
288 Dropped: 0 287 Dropped: 0
289 288
290 The output displays a line for each entry, b 289 The output displays a line for each entry, beginning with the key
291 specified in the trigger, followed by the va 290 specified in the trigger, followed by the value(s) also specified in
292 the trigger. At the beginning of the output 291 the trigger. At the beginning of the output is a line that displays
293 the trigger info, which can also be displaye 292 the trigger info, which can also be displayed by reading the
294 'trigger' file:: 293 'trigger' file::
295 294
296 # cat /sys/kernel/tracing/events/kmem/kmal !! 295 # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
297 hist:keys=call_site:vals=bytes_req:sort=hi 296 hist:keys=call_site:vals=bytes_req:sort=hitcount:size=2048 [active]
298 297
299 At the end of the output are a few lines tha 298 At the end of the output are a few lines that display the overall
300 totals for the run. The 'Hits' field shows 299 totals for the run. The 'Hits' field shows the total number of
301 times the event trigger was hit, the 'Entrie 300 times the event trigger was hit, the 'Entries' field shows the total
302 number of used entries in the hash table, an 301 number of used entries in the hash table, and the 'Dropped' field
303 shows the number of hits that were dropped b 302 shows the number of hits that were dropped because the number of
304 used entries for the run exceeded the maximu 303 used entries for the run exceeded the maximum number of entries
305 allowed for the table (normally 0, but if no 304 allowed for the table (normally 0, but if not a hint that you may
306 want to increase the size of the table using 305 want to increase the size of the table using the 'size' parameter).
307 306
308 Notice in the above output that there's an e 307 Notice in the above output that there's an extra field, 'hitcount',
309 which wasn't specified in the trigger. Also 308 which wasn't specified in the trigger. Also notice that in the
310 trigger info output, there's a parameter, 's 309 trigger info output, there's a parameter, 'sort=hitcount', which
311 wasn't specified in the trigger either. The 310 wasn't specified in the trigger either. The reason for that is that
312 every trigger implicitly keeps a count of th 311 every trigger implicitly keeps a count of the total number of hits
313 attributed to a given entry, called the 'hit 312 attributed to a given entry, called the 'hitcount'. That hitcount
314 information is explicitly displayed in the o 313 information is explicitly displayed in the output, and in the
315 absence of a user-specified sort parameter, 314 absence of a user-specified sort parameter, is used as the default
316 sort field. 315 sort field.
317 316
318 The value 'hitcount' can be used in place of 317 The value 'hitcount' can be used in place of an explicit value in
319 the 'values' parameter if you don't really n 318 the 'values' parameter if you don't really need to have any
320 particular field summed and are mainly inter 319 particular field summed and are mainly interested in hit
321 frequencies. 320 frequencies.
322 321
323 To turn the hist trigger off, simply call up 322 To turn the hist trigger off, simply call up the trigger in the
324 command history and re-execute it with a '!' 323 command history and re-execute it with a '!' prepended::
325 324
326 # echo '!hist:key=call_site:val=bytes_req' 325 # echo '!hist:key=call_site:val=bytes_req' > \
327 /sys/kernel/tracing/events/kmem/kma !! 326 /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
328 327
329 Finally, notice that the call_site as displa 328 Finally, notice that the call_site as displayed in the output above
330 isn't really very useful. It's an address, 329 isn't really very useful. It's an address, but normally addresses
331 are displayed in hex. To have a numeric fie 330 are displayed in hex. To have a numeric field displayed as a hex
332 value, simply append '.hex' to the field nam 331 value, simply append '.hex' to the field name in the trigger::
333 332
334 # echo 'hist:key=call_site.hex:val=bytes_r 333 # echo 'hist:key=call_site.hex:val=bytes_req' > \
335 /sys/kernel/tracing/events/kmem/kma !! 334 /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
336 335
337 # cat /sys/kernel/tracing/events/kmem/kmal !! 336 # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist
338 # trigger info: hist:keys=call_site.hex:va 337 # trigger info: hist:keys=call_site.hex:vals=bytes_req:sort=hitcount:size=2048 [active]
339 338
340 { call_site: ffffffffa026b291 } hitcount: 339 { call_site: ffffffffa026b291 } hitcount: 1 bytes_req: 433
341 { call_site: ffffffffa07186ff } hitcount: 340 { call_site: ffffffffa07186ff } hitcount: 1 bytes_req: 176
342 { call_site: ffffffff811ae721 } hitcount: 341 { call_site: ffffffff811ae721 } hitcount: 1 bytes_req: 16384
343 { call_site: ffffffff811c5134 } hitcount: 342 { call_site: ffffffff811c5134 } hitcount: 1 bytes_req: 8
344 { call_site: ffffffffa04a9ebb } hitcount: 343 { call_site: ffffffffa04a9ebb } hitcount: 1 bytes_req: 511
345 { call_site: ffffffff8122e0a6 } hitcount: 344 { call_site: ffffffff8122e0a6 } hitcount: 1 bytes_req: 12
346 { call_site: ffffffff8107da84 } hitcount: 345 { call_site: ffffffff8107da84 } hitcount: 1 bytes_req: 152
347 { call_site: ffffffff812d8246 } hitcount: 346 { call_site: ffffffff812d8246 } hitcount: 1 bytes_req: 24
348 { call_site: ffffffff811dc1e5 } hitcount: 347 { call_site: ffffffff811dc1e5 } hitcount: 3 bytes_req: 144
349 { call_site: ffffffffa02515e8 } hitcount: 348 { call_site: ffffffffa02515e8 } hitcount: 3 bytes_req: 648
350 { call_site: ffffffff81258159 } hitcount: 349 { call_site: ffffffff81258159 } hitcount: 3 bytes_req: 144
351 { call_site: ffffffff811c80f4 } hitcount: 350 { call_site: ffffffff811c80f4 } hitcount: 4 bytes_req: 544
352 . 351 .
353 . 352 .
354 . 353 .
355 { call_site: ffffffffa06c7646 } hitcount: 354 { call_site: ffffffffa06c7646 } hitcount: 106 bytes_req: 8024
356 { call_site: ffffffffa06cb246 } hitcount: 355 { call_site: ffffffffa06cb246 } hitcount: 132 bytes_req: 31680
357 { call_site: ffffffffa06cef7a } hitcount: 356 { call_site: ffffffffa06cef7a } hitcount: 132 bytes_req: 2112
358 { call_site: ffffffff8137e399 } hitcount: 357 { call_site: ffffffff8137e399 } hitcount: 132 bytes_req: 23232
359 { call_site: ffffffffa06c941c } hitcount: 358 { call_site: ffffffffa06c941c } hitcount: 185 bytes_req: 171360
360 { call_site: ffffffffa06f2a66 } hitcount: 359 { call_site: ffffffffa06f2a66 } hitcount: 185 bytes_req: 26640
361 { call_site: ffffffffa036a70e } hitcount: 360 { call_site: ffffffffa036a70e } hitcount: 265 bytes_req: 10600
362 { call_site: ffffffff81325447 } hitcount: 361 { call_site: ffffffff81325447 } hitcount: 292 bytes_req: 584
363 { call_site: ffffffffa072da3c } hitcount: 362 { call_site: ffffffffa072da3c } hitcount: 446 bytes_req: 60656
364 { call_site: ffffffffa036b1f2 } hitcount: 363 { call_site: ffffffffa036b1f2 } hitcount: 526 bytes_req: 29456
365 { call_site: ffffffffa0099c06 } hitcount: 364 { call_site: ffffffffa0099c06 } hitcount: 1780 bytes_req: 35600
366 365
367 Totals: 366 Totals:
368 Hits: 4775 367 Hits: 4775
369 Entries: 46 368 Entries: 46
370 Dropped: 0 369 Dropped: 0
371 370
372 Even that's only marginally more useful - wh 371 Even that's only marginally more useful - while hex values do look
373 more like addresses, what users are typicall 372 more like addresses, what users are typically more interested in
374 when looking at text addresses are the corre 373 when looking at text addresses are the corresponding symbols
375 instead. To have an address displayed as sy 374 instead. To have an address displayed as symbolic value instead,
376 simply append '.sym' or '.sym-offset' to the 375 simply append '.sym' or '.sym-offset' to the field name in the
377 trigger:: 376 trigger::
378 377
379 # echo 'hist:key=call_site.sym:val=bytes_r 378 # echo 'hist:key=call_site.sym:val=bytes_req' > \
380 /sys/kernel/tracing/events/kmem/kma !! 379 /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
381 380
382 # cat /sys/kernel/tracing/events/kmem/kmal !! 381 # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist
383 # trigger info: hist:keys=call_site.sym:va 382 # trigger info: hist:keys=call_site.sym:vals=bytes_req:sort=hitcount:size=2048 [active]
384 383
385 { call_site: [ffffffff810adcb9] syslog_pri 384 { call_site: [ffffffff810adcb9] syslog_print_all } hitcount: 1 bytes_req: 1024
386 { call_site: [ffffffff8154bc62] usb_contro 385 { call_site: [ffffffff8154bc62] usb_control_msg } hitcount: 1 bytes_req: 8
387 { call_site: [ffffffffa00bf6fe] hidraw_sen 386 { call_site: [ffffffffa00bf6fe] hidraw_send_report [hid] } hitcount: 1 bytes_req: 7
388 { call_site: [ffffffff8154acbe] usb_alloc_ 387 { call_site: [ffffffff8154acbe] usb_alloc_urb } hitcount: 1 bytes_req: 192
389 { call_site: [ffffffffa00bf1ca] hidraw_rep 388 { call_site: [ffffffffa00bf1ca] hidraw_report_event [hid] } hitcount: 1 bytes_req: 7
390 { call_site: [ffffffff811e3a25] __seq_open 389 { call_site: [ffffffff811e3a25] __seq_open_private } hitcount: 1 bytes_req: 40
391 { call_site: [ffffffff8109524a] alloc_fair 390 { call_site: [ffffffff8109524a] alloc_fair_sched_group } hitcount: 2 bytes_req: 128
392 { call_site: [ffffffff811febd5] fsnotify_a 391 { call_site: [ffffffff811febd5] fsnotify_alloc_group } hitcount: 2 bytes_req: 528
393 { call_site: [ffffffff81440f58] __tty_buff 392 { call_site: [ffffffff81440f58] __tty_buffer_request_room } hitcount: 2 bytes_req: 2624
394 { call_site: [ffffffff81200ba6] inotify_ne 393 { call_site: [ffffffff81200ba6] inotify_new_group } hitcount: 2 bytes_req: 96
395 { call_site: [ffffffffa05e19af] ieee80211_ 394 { call_site: [ffffffffa05e19af] ieee80211_start_tx_ba_session [mac80211] } hitcount: 2 bytes_req: 464
396 { call_site: [ffffffff81672406] tcp_get_me 395 { call_site: [ffffffff81672406] tcp_get_metrics } hitcount: 2 bytes_req: 304
397 { call_site: [ffffffff81097ec2] alloc_rt_s 396 { call_site: [ffffffff81097ec2] alloc_rt_sched_group } hitcount: 2 bytes_req: 128
398 { call_site: [ffffffff81089b05] sched_crea 397 { call_site: [ffffffff81089b05] sched_create_group } hitcount: 2 bytes_req: 1424
399 . 398 .
400 . 399 .
401 . 400 .
402 { call_site: [ffffffffa04a580c] intel_crtc 401 { call_site: [ffffffffa04a580c] intel_crtc_page_flip [i915] } hitcount: 1185 bytes_req: 123240
403 { call_site: [ffffffffa0287592] drm_mode_p 402 { call_site: [ffffffffa0287592] drm_mode_page_flip_ioctl [drm] } hitcount: 1185 bytes_req: 104280
404 { call_site: [ffffffffa04c4a3c] intel_plan 403 { call_site: [ffffffffa04c4a3c] intel_plane_duplicate_state [i915] } hitcount: 1402 bytes_req: 190672
405 { call_site: [ffffffff812891ca] ext4_find_ 404 { call_site: [ffffffff812891ca] ext4_find_extent } hitcount: 1518 bytes_req: 146208
406 { call_site: [ffffffffa029070e] drm_vma_no 405 { call_site: [ffffffffa029070e] drm_vma_node_allow [drm] } hitcount: 1746 bytes_req: 69840
407 { call_site: [ffffffffa045e7c4] i915_gem_d 406 { call_site: [ffffffffa045e7c4] i915_gem_do_execbuffer.isra.23 [i915] } hitcount: 2021 bytes_req: 792312
408 { call_site: [ffffffffa02911f2] drm_modese 407 { call_site: [ffffffffa02911f2] drm_modeset_lock_crtc [drm] } hitcount: 2592 bytes_req: 145152
409 { call_site: [ffffffffa0489a66] intel_ring 408 { call_site: [ffffffffa0489a66] intel_ring_begin [i915] } hitcount: 2629 bytes_req: 378576
410 { call_site: [ffffffffa046041c] i915_gem_e 409 { call_site: [ffffffffa046041c] i915_gem_execbuffer2 [i915] } hitcount: 2629 bytes_req: 3783248
411 { call_site: [ffffffff81325607] apparmor_f 410 { call_site: [ffffffff81325607] apparmor_file_alloc_security } hitcount: 5192 bytes_req: 10384
412 { call_site: [ffffffffa00b7c06] hid_report 411 { call_site: [ffffffffa00b7c06] hid_report_raw_event [hid] } hitcount: 5529 bytes_req: 110584
413 { call_site: [ffffffff8131ebf7] aa_alloc_t 412 { call_site: [ffffffff8131ebf7] aa_alloc_task_context } hitcount: 21943 bytes_req: 702176
414 { call_site: [ffffffff8125847d] ext4_htree 413 { call_site: [ffffffff8125847d] ext4_htree_store_dirent } hitcount: 55759 bytes_req: 5074265
415 414
416 Totals: 415 Totals:
417 Hits: 109928 416 Hits: 109928
418 Entries: 71 417 Entries: 71
419 Dropped: 0 418 Dropped: 0
420 419
421 Because the default sort key above is 'hitco 420 Because the default sort key above is 'hitcount', the above shows a
422 the list of call_sites by increasing hitcoun 421 the list of call_sites by increasing hitcount, so that at the bottom
423 we see the functions that made the most kmal 422 we see the functions that made the most kmalloc calls during the
424 run. If instead we wanted to see the top km 423 run. If instead we wanted to see the top kmalloc callers in
425 terms of the number of bytes requested rathe 424 terms of the number of bytes requested rather than the number of
426 calls, and we wanted the top caller to appea 425 calls, and we wanted the top caller to appear at the top, we can use
427 the 'sort' parameter, along with the 'descen 426 the 'sort' parameter, along with the 'descending' modifier::
428 427
429 # echo 'hist:key=call_site.sym:val=bytes_r 428 # echo 'hist:key=call_site.sym:val=bytes_req:sort=bytes_req.descending' > \
430 /sys/kernel/tracing/events/kmem/kma !! 429 /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
431 430
432 # cat /sys/kernel/tracing/events/kmem/kmal !! 431 # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist
433 # trigger info: hist:keys=call_site.sym:va 432 # trigger info: hist:keys=call_site.sym:vals=bytes_req:sort=bytes_req.descending:size=2048 [active]
434 433
435 { call_site: [ffffffffa046041c] i915_gem_e 434 { call_site: [ffffffffa046041c] i915_gem_execbuffer2 [i915] } hitcount: 2186 bytes_req: 3397464
436 { call_site: [ffffffffa045e7c4] i915_gem_d 435 { call_site: [ffffffffa045e7c4] i915_gem_do_execbuffer.isra.23 [i915] } hitcount: 1790 bytes_req: 712176
437 { call_site: [ffffffff8125847d] ext4_htree 436 { call_site: [ffffffff8125847d] ext4_htree_store_dirent } hitcount: 8132 bytes_req: 513135
438 { call_site: [ffffffff811e2a1b] seq_buf_al 437 { call_site: [ffffffff811e2a1b] seq_buf_alloc } hitcount: 106 bytes_req: 440128
439 { call_site: [ffffffffa0489a66] intel_ring 438 { call_site: [ffffffffa0489a66] intel_ring_begin [i915] } hitcount: 2186 bytes_req: 314784
440 { call_site: [ffffffff812891ca] ext4_find_ 439 { call_site: [ffffffff812891ca] ext4_find_extent } hitcount: 2174 bytes_req: 208992
441 { call_site: [ffffffff811ae8e1] __kmalloc 440 { call_site: [ffffffff811ae8e1] __kmalloc } hitcount: 8 bytes_req: 131072
442 { call_site: [ffffffffa04c4a3c] intel_plan 441 { call_site: [ffffffffa04c4a3c] intel_plane_duplicate_state [i915] } hitcount: 859 bytes_req: 116824
443 { call_site: [ffffffffa02911f2] drm_modese 442 { call_site: [ffffffffa02911f2] drm_modeset_lock_crtc [drm] } hitcount: 1834 bytes_req: 102704
444 { call_site: [ffffffffa04a580c] intel_crtc 443 { call_site: [ffffffffa04a580c] intel_crtc_page_flip [i915] } hitcount: 972 bytes_req: 101088
445 { call_site: [ffffffffa0287592] drm_mode_p 444 { call_site: [ffffffffa0287592] drm_mode_page_flip_ioctl [drm] } hitcount: 972 bytes_req: 85536
446 { call_site: [ffffffffa00b7c06] hid_report 445 { call_site: [ffffffffa00b7c06] hid_report_raw_event [hid] } hitcount: 3333 bytes_req: 66664
447 { call_site: [ffffffff8137e559] sg_kmalloc 446 { call_site: [ffffffff8137e559] sg_kmalloc } hitcount: 209 bytes_req: 61632
448 . 447 .
449 . 448 .
450 . 449 .
451 { call_site: [ffffffff81095225] alloc_fair 450 { call_site: [ffffffff81095225] alloc_fair_sched_group } hitcount: 2 bytes_req: 128
452 { call_site: [ffffffff81097ec2] alloc_rt_s 451 { call_site: [ffffffff81097ec2] alloc_rt_sched_group } hitcount: 2 bytes_req: 128
453 { call_site: [ffffffff812d8406] copy_semun 452 { call_site: [ffffffff812d8406] copy_semundo } hitcount: 2 bytes_req: 48
454 { call_site: [ffffffff81200ba6] inotify_ne 453 { call_site: [ffffffff81200ba6] inotify_new_group } hitcount: 1 bytes_req: 48
455 { call_site: [ffffffffa027121a] drm_getmag 454 { call_site: [ffffffffa027121a] drm_getmagic [drm] } hitcount: 1 bytes_req: 48
456 { call_site: [ffffffff811e3a25] __seq_open 455 { call_site: [ffffffff811e3a25] __seq_open_private } hitcount: 1 bytes_req: 40
457 { call_site: [ffffffff811c52f4] bprm_chang 456 { call_site: [ffffffff811c52f4] bprm_change_interp } hitcount: 2 bytes_req: 16
458 { call_site: [ffffffff8154bc62] usb_contro 457 { call_site: [ffffffff8154bc62] usb_control_msg } hitcount: 1 bytes_req: 8
459 { call_site: [ffffffffa00bf1ca] hidraw_rep 458 { call_site: [ffffffffa00bf1ca] hidraw_report_event [hid] } hitcount: 1 bytes_req: 7
460 { call_site: [ffffffffa00bf6fe] hidraw_sen 459 { call_site: [ffffffffa00bf6fe] hidraw_send_report [hid] } hitcount: 1 bytes_req: 7
461 460
462 Totals: 461 Totals:
463 Hits: 32133 462 Hits: 32133
464 Entries: 81 463 Entries: 81
465 Dropped: 0 464 Dropped: 0
466 465
467 To display the offset and size information i 466 To display the offset and size information in addition to the symbol
468 name, just use 'sym-offset' instead:: 467 name, just use 'sym-offset' instead::
469 468
470 # echo 'hist:key=call_site.sym-offset:val= 469 # echo 'hist:key=call_site.sym-offset:val=bytes_req:sort=bytes_req.descending' > \
471 /sys/kernel/tracing/events/kmem/kma !! 470 /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
472 471
473 # cat /sys/kernel/tracing/events/kmem/kmal !! 472 # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist
474 # trigger info: hist:keys=call_site.sym-of 473 # trigger info: hist:keys=call_site.sym-offset:vals=bytes_req:sort=bytes_req.descending:size=2048 [active]
475 474
476 { call_site: [ffffffffa046041c] i915_gem_e 475 { call_site: [ffffffffa046041c] i915_gem_execbuffer2+0x6c/0x2c0 [i915] } hitcount: 4569 bytes_req: 3163720
477 { call_site: [ffffffffa0489a66] intel_ring 476 { call_site: [ffffffffa0489a66] intel_ring_begin+0xc6/0x1f0 [i915] } hitcount: 4569 bytes_req: 657936
478 { call_site: [ffffffffa045e7c4] i915_gem_d 477 { call_site: [ffffffffa045e7c4] i915_gem_do_execbuffer.isra.23+0x694/0x1020 [i915] } hitcount: 1519 bytes_req: 472936
479 { call_site: [ffffffffa045e646] i915_gem_d 478 { call_site: [ffffffffa045e646] i915_gem_do_execbuffer.isra.23+0x516/0x1020 [i915] } hitcount: 3050 bytes_req: 211832
480 { call_site: [ffffffff811e2a1b] seq_buf_al 479 { call_site: [ffffffff811e2a1b] seq_buf_alloc+0x1b/0x50 } hitcount: 34 bytes_req: 148384
481 { call_site: [ffffffffa04a580c] intel_crtc 480 { call_site: [ffffffffa04a580c] intel_crtc_page_flip+0xbc/0x870 [i915] } hitcount: 1385 bytes_req: 144040
482 { call_site: [ffffffff811ae8e1] __kmalloc+ 481 { call_site: [ffffffff811ae8e1] __kmalloc+0x191/0x1b0 } hitcount: 8 bytes_req: 131072
483 { call_site: [ffffffffa0287592] drm_mode_p 482 { call_site: [ffffffffa0287592] drm_mode_page_flip_ioctl+0x282/0x360 [drm] } hitcount: 1385 bytes_req: 121880
484 { call_site: [ffffffffa02911f2] drm_modese 483 { call_site: [ffffffffa02911f2] drm_modeset_lock_crtc+0x32/0x100 [drm] } hitcount: 1848 bytes_req: 103488
485 { call_site: [ffffffffa04c4a3c] intel_plan 484 { call_site: [ffffffffa04c4a3c] intel_plane_duplicate_state+0x2c/0xa0 [i915] } hitcount: 461 bytes_req: 62696
486 { call_site: [ffffffffa029070e] drm_vma_no 485 { call_site: [ffffffffa029070e] drm_vma_node_allow+0x2e/0xd0 [drm] } hitcount: 1541 bytes_req: 61640
487 { call_site: [ffffffff815f8d7b] sk_prot_al 486 { call_site: [ffffffff815f8d7b] sk_prot_alloc+0xcb/0x1b0 } hitcount: 57 bytes_req: 57456
488 . 487 .
489 . 488 .
490 . 489 .
491 { call_site: [ffffffff8109524a] alloc_fair 490 { call_site: [ffffffff8109524a] alloc_fair_sched_group+0x5a/0x1a0 } hitcount: 2 bytes_req: 128
492 { call_site: [ffffffffa027b921] drm_vm_ope 491 { call_site: [ffffffffa027b921] drm_vm_open_locked+0x31/0xa0 [drm] } hitcount: 3 bytes_req: 96
493 { call_site: [ffffffff8122e266] proc_self_ 492 { call_site: [ffffffff8122e266] proc_self_follow_link+0x76/0xb0 } hitcount: 8 bytes_req: 96
494 { call_site: [ffffffff81213e80] load_elf_b 493 { call_site: [ffffffff81213e80] load_elf_binary+0x240/0x1650 } hitcount: 3 bytes_req: 84
495 { call_site: [ffffffff8154bc62] usb_contro 494 { call_site: [ffffffff8154bc62] usb_control_msg+0x42/0x110 } hitcount: 1 bytes_req: 8
496 { call_site: [ffffffffa00bf6fe] hidraw_sen 495 { call_site: [ffffffffa00bf6fe] hidraw_send_report+0x7e/0x1a0 [hid] } hitcount: 1 bytes_req: 7
497 { call_site: [ffffffffa00bf1ca] hidraw_rep 496 { call_site: [ffffffffa00bf1ca] hidraw_report_event+0x8a/0x120 [hid] } hitcount: 1 bytes_req: 7
498 497
499 Totals: 498 Totals:
500 Hits: 26098 499 Hits: 26098
501 Entries: 64 500 Entries: 64
502 Dropped: 0 501 Dropped: 0
503 502
504 We can also add multiple fields to the 'valu 503 We can also add multiple fields to the 'values' parameter. For
505 example, we might want to see the total numb 504 example, we might want to see the total number of bytes allocated
506 alongside bytes requested, and display the r 505 alongside bytes requested, and display the result sorted by bytes
507 allocated in a descending order:: 506 allocated in a descending order::
508 507
509 # echo 'hist:keys=call_site.sym:values=byt 508 # echo 'hist:keys=call_site.sym:values=bytes_req,bytes_alloc:sort=bytes_alloc.descending' > \
510 /sys/kernel/tracing/events/kmem/kma !! 509 /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
511 510
512 # cat /sys/kernel/tracing/events/kmem/kmal !! 511 # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist
513 # trigger info: hist:keys=call_site.sym:va 512 # trigger info: hist:keys=call_site.sym:vals=bytes_req,bytes_alloc:sort=bytes_alloc.descending:size=2048 [active]
514 513
515 { call_site: [ffffffffa046041c] i915_gem_e 514 { call_site: [ffffffffa046041c] i915_gem_execbuffer2 [i915] } hitcount: 7403 bytes_req: 4084360 bytes_alloc: 5958016
516 { call_site: [ffffffff811e2a1b] seq_buf_al 515 { call_site: [ffffffff811e2a1b] seq_buf_alloc } hitcount: 541 bytes_req: 2213968 bytes_alloc: 2228224
517 { call_site: [ffffffffa0489a66] intel_ring 516 { call_site: [ffffffffa0489a66] intel_ring_begin [i915] } hitcount: 7404 bytes_req: 1066176 bytes_alloc: 1421568
518 { call_site: [ffffffffa045e7c4] i915_gem_d 517 { call_site: [ffffffffa045e7c4] i915_gem_do_execbuffer.isra.23 [i915] } hitcount: 1565 bytes_req: 557368 bytes_alloc: 1037760
519 { call_site: [ffffffff8125847d] ext4_htree 518 { call_site: [ffffffff8125847d] ext4_htree_store_dirent } hitcount: 9557 bytes_req: 595778 bytes_alloc: 695744
520 { call_site: [ffffffffa045e646] i915_gem_d 519 { call_site: [ffffffffa045e646] i915_gem_do_execbuffer.isra.23 [i915] } hitcount: 5839 bytes_req: 430680 bytes_alloc: 470400
521 { call_site: [ffffffffa04c4a3c] intel_plan 520 { call_site: [ffffffffa04c4a3c] intel_plane_duplicate_state [i915] } hitcount: 2388 bytes_req: 324768 bytes_alloc: 458496
522 { call_site: [ffffffffa02911f2] drm_modese 521 { call_site: [ffffffffa02911f2] drm_modeset_lock_crtc [drm] } hitcount: 3911 bytes_req: 219016 bytes_alloc: 250304
523 { call_site: [ffffffff815f8d7b] sk_prot_al 522 { call_site: [ffffffff815f8d7b] sk_prot_alloc } hitcount: 235 bytes_req: 236880 bytes_alloc: 240640
524 { call_site: [ffffffff8137e559] sg_kmalloc 523 { call_site: [ffffffff8137e559] sg_kmalloc } hitcount: 557 bytes_req: 169024 bytes_alloc: 221760
525 { call_site: [ffffffffa00b7c06] hid_report 524 { call_site: [ffffffffa00b7c06] hid_report_raw_event [hid] } hitcount: 9378 bytes_req: 187548 bytes_alloc: 206312
526 { call_site: [ffffffffa04a580c] intel_crtc 525 { call_site: [ffffffffa04a580c] intel_crtc_page_flip [i915] } hitcount: 1519 bytes_req: 157976 bytes_alloc: 194432
527 . 526 .
528 . 527 .
529 . 528 .
530 { call_site: [ffffffff8109bd3b] sched_auto 529 { call_site: [ffffffff8109bd3b] sched_autogroup_create_attach } hitcount: 2 bytes_req: 144 bytes_alloc: 192
531 { call_site: [ffffffff81097ee8] alloc_rt_s 530 { call_site: [ffffffff81097ee8] alloc_rt_sched_group } hitcount: 2 bytes_req: 128 bytes_alloc: 128
532 { call_site: [ffffffff8109524a] alloc_fair 531 { call_site: [ffffffff8109524a] alloc_fair_sched_group } hitcount: 2 bytes_req: 128 bytes_alloc: 128
533 { call_site: [ffffffff81095225] alloc_fair 532 { call_site: [ffffffff81095225] alloc_fair_sched_group } hitcount: 2 bytes_req: 128 bytes_alloc: 128
534 { call_site: [ffffffff81097ec2] alloc_rt_s 533 { call_site: [ffffffff81097ec2] alloc_rt_sched_group } hitcount: 2 bytes_req: 128 bytes_alloc: 128
535 { call_site: [ffffffff81213e80] load_elf_b 534 { call_site: [ffffffff81213e80] load_elf_binary } hitcount: 3 bytes_req: 84 bytes_alloc: 96
536 { call_site: [ffffffff81079a2e] kthread_cr 535 { call_site: [ffffffff81079a2e] kthread_create_on_node } hitcount: 1 bytes_req: 56 bytes_alloc: 64
537 { call_site: [ffffffffa00bf6fe] hidraw_sen 536 { call_site: [ffffffffa00bf6fe] hidraw_send_report [hid] } hitcount: 1 bytes_req: 7 bytes_alloc: 8
538 { call_site: [ffffffff8154bc62] usb_contro 537 { call_site: [ffffffff8154bc62] usb_control_msg } hitcount: 1 bytes_req: 8 bytes_alloc: 8
539 { call_site: [ffffffffa00bf1ca] hidraw_rep 538 { call_site: [ffffffffa00bf1ca] hidraw_report_event [hid] } hitcount: 1 bytes_req: 7 bytes_alloc: 8
540 539
541 Totals: 540 Totals:
542 Hits: 66598 541 Hits: 66598
543 Entries: 65 542 Entries: 65
544 Dropped: 0 543 Dropped: 0
545 544
546 Finally, to finish off our kmalloc example, 545 Finally, to finish off our kmalloc example, instead of simply having
547 the hist trigger display symbolic call_sites 546 the hist trigger display symbolic call_sites, we can have the hist
548 trigger additionally display the complete se 547 trigger additionally display the complete set of kernel stack traces
549 that led to each call_site. To do that, we 548 that led to each call_site. To do that, we simply use the special
550 value 'common_stacktrace' for the key parame !! 549 value 'stacktrace' for the key parameter::
551 550
552 # echo 'hist:keys=common_stacktrace:values !! 551 # echo 'hist:keys=stacktrace:values=bytes_req,bytes_alloc:sort=bytes_alloc' > \
553 /sys/kernel/tracing/events/kmem/kma !! 552 /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
554 553
555 The above trigger will use the kernel stack 554 The above trigger will use the kernel stack trace in effect when an
556 event is triggered as the key for the hash t 555 event is triggered as the key for the hash table. This allows the
557 enumeration of every kernel callpath that le 556 enumeration of every kernel callpath that led up to a particular
558 event, along with a running total of any of 557 event, along with a running total of any of the event fields for
559 that event. Here we tally bytes requested a 558 that event. Here we tally bytes requested and bytes allocated for
560 every callpath in the system that led up to 559 every callpath in the system that led up to a kmalloc (in this case
561 every callpath to a kmalloc for a kernel com 560 every callpath to a kmalloc for a kernel compile)::
562 561
563 # cat /sys/kernel/tracing/events/kmem/kmal !! 562 # cat /sys/kernel/debug/tracing/events/kmem/kmalloc/hist
564 # trigger info: hist:keys=common_stacktrac !! 563 # trigger info: hist:keys=stacktrace:vals=bytes_req,bytes_alloc:sort=bytes_alloc:size=2048 [active]
565 564
566 { common_stacktrace: !! 565 { stacktrace:
567 __kmalloc_track_caller+0x10b/0x1a0 566 __kmalloc_track_caller+0x10b/0x1a0
568 kmemdup+0x20/0x50 567 kmemdup+0x20/0x50
569 hidraw_report_event+0x8a/0x120 [hid] 568 hidraw_report_event+0x8a/0x120 [hid]
570 hid_report_raw_event+0x3ea/0x440 [hid 569 hid_report_raw_event+0x3ea/0x440 [hid]
571 hid_input_report+0x112/0x190 [hid] 570 hid_input_report+0x112/0x190 [hid]
572 hid_irq_in+0xc2/0x260 [usbhid] 571 hid_irq_in+0xc2/0x260 [usbhid]
573 __usb_hcd_giveback_urb+0x72/0x120 572 __usb_hcd_giveback_urb+0x72/0x120
574 usb_giveback_urb_bh+0x9e/0xe0 573 usb_giveback_urb_bh+0x9e/0xe0
575 tasklet_hi_action+0xf8/0x100 574 tasklet_hi_action+0xf8/0x100
576 __do_softirq+0x114/0x2c0 575 __do_softirq+0x114/0x2c0
577 irq_exit+0xa5/0xb0 576 irq_exit+0xa5/0xb0
578 do_IRQ+0x5a/0xf0 577 do_IRQ+0x5a/0xf0
579 ret_from_intr+0x0/0x30 578 ret_from_intr+0x0/0x30
580 cpuidle_enter+0x17/0x20 579 cpuidle_enter+0x17/0x20
581 cpu_startup_entry+0x315/0x3e0 580 cpu_startup_entry+0x315/0x3e0
582 rest_init+0x7c/0x80 581 rest_init+0x7c/0x80
583 } hitcount: 3 bytes_req: 582 } hitcount: 3 bytes_req: 21 bytes_alloc: 24
584 { common_stacktrace: !! 583 { stacktrace:
585 __kmalloc_track_caller+0x10b/0x1a0 584 __kmalloc_track_caller+0x10b/0x1a0
586 kmemdup+0x20/0x50 585 kmemdup+0x20/0x50
587 hidraw_report_event+0x8a/0x120 [hid] 586 hidraw_report_event+0x8a/0x120 [hid]
588 hid_report_raw_event+0x3ea/0x440 [hid 587 hid_report_raw_event+0x3ea/0x440 [hid]
589 hid_input_report+0x112/0x190 [hid] 588 hid_input_report+0x112/0x190 [hid]
590 hid_irq_in+0xc2/0x260 [usbhid] 589 hid_irq_in+0xc2/0x260 [usbhid]
591 __usb_hcd_giveback_urb+0x72/0x120 590 __usb_hcd_giveback_urb+0x72/0x120
592 usb_giveback_urb_bh+0x9e/0xe0 591 usb_giveback_urb_bh+0x9e/0xe0
593 tasklet_hi_action+0xf8/0x100 592 tasklet_hi_action+0xf8/0x100
594 __do_softirq+0x114/0x2c0 593 __do_softirq+0x114/0x2c0
595 irq_exit+0xa5/0xb0 594 irq_exit+0xa5/0xb0
596 do_IRQ+0x5a/0xf0 595 do_IRQ+0x5a/0xf0
597 ret_from_intr+0x0/0x30 596 ret_from_intr+0x0/0x30
598 } hitcount: 3 bytes_req: 597 } hitcount: 3 bytes_req: 21 bytes_alloc: 24
599 { common_stacktrace: !! 598 { stacktrace:
600 kmem_cache_alloc_trace+0xeb/0x150 599 kmem_cache_alloc_trace+0xeb/0x150
601 aa_alloc_task_context+0x27/0x40 600 aa_alloc_task_context+0x27/0x40
602 apparmor_cred_prepare+0x1f/0x50 601 apparmor_cred_prepare+0x1f/0x50
603 security_prepare_creds+0x16/0x20 602 security_prepare_creds+0x16/0x20
604 prepare_creds+0xdf/0x1a0 603 prepare_creds+0xdf/0x1a0
605 SyS_capset+0xb5/0x200 604 SyS_capset+0xb5/0x200
606 system_call_fastpath+0x12/0x6a 605 system_call_fastpath+0x12/0x6a
607 } hitcount: 1 bytes_req: 606 } hitcount: 1 bytes_req: 32 bytes_alloc: 32
608 . 607 .
609 . 608 .
610 . 609 .
611 { common_stacktrace: !! 610 { stacktrace:
612 __kmalloc+0x11b/0x1b0 611 __kmalloc+0x11b/0x1b0
613 i915_gem_execbuffer2+0x6c/0x2c0 [i915 612 i915_gem_execbuffer2+0x6c/0x2c0 [i915]
614 drm_ioctl+0x349/0x670 [drm] 613 drm_ioctl+0x349/0x670 [drm]
615 do_vfs_ioctl+0x2f0/0x4f0 614 do_vfs_ioctl+0x2f0/0x4f0
616 SyS_ioctl+0x81/0xa0 615 SyS_ioctl+0x81/0xa0
617 system_call_fastpath+0x12/0x6a 616 system_call_fastpath+0x12/0x6a
618 } hitcount: 17726 bytes_req: 13944 617 } hitcount: 17726 bytes_req: 13944120 bytes_alloc: 19593808
619 { common_stacktrace: !! 618 { stacktrace:
620 __kmalloc+0x11b/0x1b0 619 __kmalloc+0x11b/0x1b0
621 load_elf_phdrs+0x76/0xa0 620 load_elf_phdrs+0x76/0xa0
622 load_elf_binary+0x102/0x1650 621 load_elf_binary+0x102/0x1650
623 search_binary_handler+0x97/0x1d0 622 search_binary_handler+0x97/0x1d0
624 do_execveat_common.isra.34+0x551/0x6e 623 do_execveat_common.isra.34+0x551/0x6e0
625 SyS_execve+0x3a/0x50 624 SyS_execve+0x3a/0x50
626 return_from_execve+0x0/0x23 625 return_from_execve+0x0/0x23
627 } hitcount: 33348 bytes_req: 17152 626 } hitcount: 33348 bytes_req: 17152128 bytes_alloc: 20226048
628 { common_stacktrace: !! 627 { stacktrace:
629 kmem_cache_alloc_trace+0xeb/0x150 628 kmem_cache_alloc_trace+0xeb/0x150
630 apparmor_file_alloc_security+0x27/0x4 629 apparmor_file_alloc_security+0x27/0x40
631 security_file_alloc+0x16/0x20 630 security_file_alloc+0x16/0x20
632 get_empty_filp+0x93/0x1c0 631 get_empty_filp+0x93/0x1c0
633 path_openat+0x31/0x5f0 632 path_openat+0x31/0x5f0
634 do_filp_open+0x3a/0x90 633 do_filp_open+0x3a/0x90
635 do_sys_open+0x128/0x220 634 do_sys_open+0x128/0x220
636 SyS_open+0x1e/0x20 635 SyS_open+0x1e/0x20
637 system_call_fastpath+0x12/0x6a 636 system_call_fastpath+0x12/0x6a
638 } hitcount: 4766422 bytes_req: 9532 637 } hitcount: 4766422 bytes_req: 9532844 bytes_alloc: 38131376
639 { common_stacktrace: !! 638 { stacktrace:
640 __kmalloc+0x11b/0x1b0 639 __kmalloc+0x11b/0x1b0
641 seq_buf_alloc+0x1b/0x50 640 seq_buf_alloc+0x1b/0x50
642 seq_read+0x2cc/0x370 641 seq_read+0x2cc/0x370
643 proc_reg_read+0x3d/0x80 642 proc_reg_read+0x3d/0x80
644 __vfs_read+0x28/0xe0 643 __vfs_read+0x28/0xe0
645 vfs_read+0x86/0x140 644 vfs_read+0x86/0x140
646 SyS_read+0x46/0xb0 645 SyS_read+0x46/0xb0
647 system_call_fastpath+0x12/0x6a 646 system_call_fastpath+0x12/0x6a
648 } hitcount: 19133 bytes_req: 78368 647 } hitcount: 19133 bytes_req: 78368768 bytes_alloc: 78368768
649 648
650 Totals: 649 Totals:
651 Hits: 6085872 650 Hits: 6085872
652 Entries: 253 651 Entries: 253
653 Dropped: 0 652 Dropped: 0
654 653
655 If you key a hist trigger on common_pid, in 654 If you key a hist trigger on common_pid, in order for example to
656 gather and display sorted totals for each pr 655 gather and display sorted totals for each process, you can use the
657 special .execname modifier to display the ex 656 special .execname modifier to display the executable names for the
658 processes in the table rather than raw pids. 657 processes in the table rather than raw pids. The example below
659 keeps a per-process sum of total bytes read: 658 keeps a per-process sum of total bytes read::
660 659
661 # echo 'hist:key=common_pid.execname:val=c 660 # echo 'hist:key=common_pid.execname:val=count:sort=count.descending' > \
662 /sys/kernel/tracing/events/syscalls !! 661 /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/trigger
663 662
664 # cat /sys/kernel/tracing/events/syscalls/ !! 663 # cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/hist
665 # trigger info: hist:keys=common_pid.execn 664 # trigger info: hist:keys=common_pid.execname:vals=count:sort=count.descending:size=2048 [active]
666 665
667 { common_pid: gnome-terminal [ 3196] 666 { common_pid: gnome-terminal [ 3196] } hitcount: 280 count: 1093512
668 { common_pid: Xorg [ 1309] 667 { common_pid: Xorg [ 1309] } hitcount: 525 count: 256640
669 { common_pid: compiz [ 2889] 668 { common_pid: compiz [ 2889] } hitcount: 59 count: 254400
670 { common_pid: bash [ 8710] 669 { common_pid: bash [ 8710] } hitcount: 3 count: 66369
671 { common_pid: dbus-daemon-lau [ 8703] 670 { common_pid: dbus-daemon-lau [ 8703] } hitcount: 49 count: 47739
672 { common_pid: irqbalance [ 1252] 671 { common_pid: irqbalance [ 1252] } hitcount: 27 count: 27648
673 { common_pid: 01ifupdown [ 8705] 672 { common_pid: 01ifupdown [ 8705] } hitcount: 3 count: 17216
674 { common_pid: dbus-daemon [ 772] 673 { common_pid: dbus-daemon [ 772] } hitcount: 10 count: 12396
675 { common_pid: Socket Thread [ 8342] 674 { common_pid: Socket Thread [ 8342] } hitcount: 11 count: 11264
676 { common_pid: nm-dhcp-client. [ 8701] 675 { common_pid: nm-dhcp-client. [ 8701] } hitcount: 6 count: 7424
677 { common_pid: gmain [ 1315] 676 { common_pid: gmain [ 1315] } hitcount: 18 count: 6336
678 . 677 .
679 . 678 .
680 . 679 .
681 { common_pid: postgres [ 1892] 680 { common_pid: postgres [ 1892] } hitcount: 2 count: 32
682 { common_pid: postgres [ 1891] 681 { common_pid: postgres [ 1891] } hitcount: 2 count: 32
683 { common_pid: gmain [ 8704] 682 { common_pid: gmain [ 8704] } hitcount: 2 count: 32
684 { common_pid: upstart-dbus-br [ 2740] 683 { common_pid: upstart-dbus-br [ 2740] } hitcount: 21 count: 21
685 { common_pid: nm-dispatcher.a [ 8696] 684 { common_pid: nm-dispatcher.a [ 8696] } hitcount: 1 count: 16
686 { common_pid: indicator-datet [ 2904] 685 { common_pid: indicator-datet [ 2904] } hitcount: 1 count: 16
687 { common_pid: gdbus [ 2998] 686 { common_pid: gdbus [ 2998] } hitcount: 1 count: 16
688 { common_pid: rtkit-daemon [ 2052] 687 { common_pid: rtkit-daemon [ 2052] } hitcount: 1 count: 8
689 { common_pid: init [ 1] 688 { common_pid: init [ 1] } hitcount: 2 count: 2
690 689
691 Totals: 690 Totals:
692 Hits: 2116 691 Hits: 2116
693 Entries: 51 692 Entries: 51
694 Dropped: 0 693 Dropped: 0
695 694
696 Similarly, if you key a hist trigger on sysc 695 Similarly, if you key a hist trigger on syscall id, for example to
697 gather and display a list of systemwide sysc 696 gather and display a list of systemwide syscall hits, you can use
698 the special .syscall modifier to display the 697 the special .syscall modifier to display the syscall names rather
699 than raw ids. The example below keeps a run 698 than raw ids. The example below keeps a running total of syscall
700 counts for the system during the run:: 699 counts for the system during the run::
701 700
702 # echo 'hist:key=id.syscall:val=hitcount' 701 # echo 'hist:key=id.syscall:val=hitcount' > \
703 /sys/kernel/tracing/events/raw_sysc !! 702 /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger
704 703
705 # cat /sys/kernel/tracing/events/raw_sysca !! 704 # cat /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/hist
706 # trigger info: hist:keys=id.syscall:vals= 705 # trigger info: hist:keys=id.syscall:vals=hitcount:sort=hitcount:size=2048 [active]
707 706
708 { id: sys_fsync [ 74] 707 { id: sys_fsync [ 74] } hitcount: 1
709 { id: sys_newuname [ 63] 708 { id: sys_newuname [ 63] } hitcount: 1
710 { id: sys_prctl [157] 709 { id: sys_prctl [157] } hitcount: 1
711 { id: sys_statfs [137] 710 { id: sys_statfs [137] } hitcount: 1
712 { id: sys_symlink [ 88] 711 { id: sys_symlink [ 88] } hitcount: 1
713 { id: sys_sendmmsg [307] 712 { id: sys_sendmmsg [307] } hitcount: 1
714 { id: sys_semctl [ 66] 713 { id: sys_semctl [ 66] } hitcount: 1
715 { id: sys_readlink [ 89] 714 { id: sys_readlink [ 89] } hitcount: 3
716 { id: sys_bind [ 49] 715 { id: sys_bind [ 49] } hitcount: 3
717 { id: sys_getsockname [ 51] 716 { id: sys_getsockname [ 51] } hitcount: 3
718 { id: sys_unlink [ 87] 717 { id: sys_unlink [ 87] } hitcount: 3
719 { id: sys_rename [ 82] 718 { id: sys_rename [ 82] } hitcount: 4
720 { id: unknown_syscall [ 58] 719 { id: unknown_syscall [ 58] } hitcount: 4
721 { id: sys_connect [ 42] 720 { id: sys_connect [ 42] } hitcount: 4
722 { id: sys_getpid [ 39] 721 { id: sys_getpid [ 39] } hitcount: 4
723 . 722 .
724 . 723 .
725 . 724 .
726 { id: sys_rt_sigprocmask [ 14] 725 { id: sys_rt_sigprocmask [ 14] } hitcount: 952
727 { id: sys_futex [202] 726 { id: sys_futex [202] } hitcount: 1534
728 { id: sys_write [ 1] 727 { id: sys_write [ 1] } hitcount: 2689
729 { id: sys_setitimer [ 38] 728 { id: sys_setitimer [ 38] } hitcount: 2797
730 { id: sys_read [ 0] 729 { id: sys_read [ 0] } hitcount: 3202
731 { id: sys_select [ 23] 730 { id: sys_select [ 23] } hitcount: 3773
732 { id: sys_writev [ 20] 731 { id: sys_writev [ 20] } hitcount: 4531
733 { id: sys_poll [ 7] 732 { id: sys_poll [ 7] } hitcount: 8314
734 { id: sys_recvmsg [ 47] 733 { id: sys_recvmsg [ 47] } hitcount: 13738
735 { id: sys_ioctl [ 16] 734 { id: sys_ioctl [ 16] } hitcount: 21843
736 735
737 Totals: 736 Totals:
738 Hits: 67612 737 Hits: 67612
739 Entries: 72 738 Entries: 72
740 Dropped: 0 739 Dropped: 0
741 740
742 The syscall counts above provide a rough ove 741 The syscall counts above provide a rough overall picture of system
743 call activity on the system; we can see for 742 call activity on the system; we can see for example that the most
744 popular system call on this system was the ' 743 popular system call on this system was the 'sys_ioctl' system call.
745 744
746 We can use 'compound' keys to refine that nu 745 We can use 'compound' keys to refine that number and provide some
747 further insight as to which processes exactl 746 further insight as to which processes exactly contribute to the
748 overall ioctl count. 747 overall ioctl count.
749 748
750 The command below keeps a hitcount for every 749 The command below keeps a hitcount for every unique combination of
751 system call id and pid - the end result is e 750 system call id and pid - the end result is essentially a table
752 that keeps a per-pid sum of system call hits 751 that keeps a per-pid sum of system call hits. The results are
753 sorted using the system call id as the prima 752 sorted using the system call id as the primary key, and the
754 hitcount sum as the secondary key:: 753 hitcount sum as the secondary key::
755 754
756 # echo 'hist:key=id.syscall,common_pid.exe 755 # echo 'hist:key=id.syscall,common_pid.execname:val=hitcount:sort=id,hitcount' > \
757 /sys/kernel/tracing/events/raw_sysc !! 756 /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger
758 757
759 # cat /sys/kernel/tracing/events/raw_sysca !! 758 # cat /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/hist
760 # trigger info: hist:keys=id.syscall,commo 759 # trigger info: hist:keys=id.syscall,common_pid.execname:vals=hitcount:sort=id.syscall,hitcount:size=2048 [active]
761 760
762 { id: sys_read [ 0], 761 { id: sys_read [ 0], common_pid: rtkit-daemon [ 1877] } hitcount: 1
763 { id: sys_read [ 0], 762 { id: sys_read [ 0], common_pid: gdbus [ 2976] } hitcount: 1
764 { id: sys_read [ 0], 763 { id: sys_read [ 0], common_pid: console-kit-dae [ 3400] } hitcount: 1
765 { id: sys_read [ 0], 764 { id: sys_read [ 0], common_pid: postgres [ 1865] } hitcount: 1
766 { id: sys_read [ 0], 765 { id: sys_read [ 0], common_pid: deja-dup-monito [ 3543] } hitcount: 2
767 { id: sys_read [ 0], 766 { id: sys_read [ 0], common_pid: NetworkManager [ 890] } hitcount: 2
768 { id: sys_read [ 0], 767 { id: sys_read [ 0], common_pid: evolution-calen [ 3048] } hitcount: 2
769 { id: sys_read [ 0], 768 { id: sys_read [ 0], common_pid: postgres [ 1864] } hitcount: 2
770 { id: sys_read [ 0], 769 { id: sys_read [ 0], common_pid: nm-applet [ 3022] } hitcount: 2
771 { id: sys_read [ 0], 770 { id: sys_read [ 0], common_pid: whoopsie [ 1212] } hitcount: 2
772 . 771 .
773 . 772 .
774 . 773 .
775 { id: sys_ioctl [ 16], 774 { id: sys_ioctl [ 16], common_pid: bash [ 8479] } hitcount: 1
776 { id: sys_ioctl [ 16], 775 { id: sys_ioctl [ 16], common_pid: bash [ 3472] } hitcount: 12
777 { id: sys_ioctl [ 16], 776 { id: sys_ioctl [ 16], common_pid: gnome-terminal [ 3199] } hitcount: 16
778 { id: sys_ioctl [ 16], 777 { id: sys_ioctl [ 16], common_pid: Xorg [ 1267] } hitcount: 1808
779 { id: sys_ioctl [ 16], 778 { id: sys_ioctl [ 16], common_pid: compiz [ 2994] } hitcount: 5580
780 . 779 .
781 . 780 .
782 . 781 .
783 { id: sys_waitid [247], 782 { id: sys_waitid [247], common_pid: upstart-dbus-br [ 2690] } hitcount: 3
784 { id: sys_waitid [247], 783 { id: sys_waitid [247], common_pid: upstart-dbus-br [ 2688] } hitcount: 16
785 { id: sys_inotify_add_watch [254], 784 { id: sys_inotify_add_watch [254], common_pid: gmain [ 975] } hitcount: 2
786 { id: sys_inotify_add_watch [254], 785 { id: sys_inotify_add_watch [254], common_pid: gmain [ 3204] } hitcount: 4
787 { id: sys_inotify_add_watch [254], 786 { id: sys_inotify_add_watch [254], common_pid: gmain [ 2888] } hitcount: 4
788 { id: sys_inotify_add_watch [254], 787 { id: sys_inotify_add_watch [254], common_pid: gmain [ 3003] } hitcount: 4
789 { id: sys_inotify_add_watch [254], 788 { id: sys_inotify_add_watch [254], common_pid: gmain [ 2873] } hitcount: 4
790 { id: sys_inotify_add_watch [254], 789 { id: sys_inotify_add_watch [254], common_pid: gmain [ 3196] } hitcount: 6
791 { id: sys_openat [257], 790 { id: sys_openat [257], common_pid: java [ 2623] } hitcount: 2
792 { id: sys_eventfd2 [290], 791 { id: sys_eventfd2 [290], common_pid: ibus-ui-gtk3 [ 2760] } hitcount: 4
793 { id: sys_eventfd2 [290], 792 { id: sys_eventfd2 [290], common_pid: compiz [ 2994] } hitcount: 6
794 793
795 Totals: 794 Totals:
796 Hits: 31536 795 Hits: 31536
797 Entries: 323 796 Entries: 323
798 Dropped: 0 797 Dropped: 0
799 798
800 The above list does give us a breakdown of t 799 The above list does give us a breakdown of the ioctl syscall by
801 pid, but it also gives us quite a bit more t 800 pid, but it also gives us quite a bit more than that, which we
802 don't really care about at the moment. Sinc 801 don't really care about at the moment. Since we know the syscall
803 id for sys_ioctl (16, displayed next to the 802 id for sys_ioctl (16, displayed next to the sys_ioctl name), we
804 can use that to filter out all the other sys 803 can use that to filter out all the other syscalls::
805 804
806 # echo 'hist:key=id.syscall,common_pid.exe 805 # echo 'hist:key=id.syscall,common_pid.execname:val=hitcount:sort=id,hitcount if id == 16' > \
807 /sys/kernel/tracing/events/raw_sysc !! 806 /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger
808 807
809 # cat /sys/kernel/tracing/events/raw_sysca !! 808 # cat /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/hist
810 # trigger info: hist:keys=id.syscall,commo 809 # trigger info: hist:keys=id.syscall,common_pid.execname:vals=hitcount:sort=id.syscall,hitcount:size=2048 if id == 16 [active]
811 810
812 { id: sys_ioctl [ 16], 811 { id: sys_ioctl [ 16], common_pid: gmain [ 2769] } hitcount: 1
813 { id: sys_ioctl [ 16], 812 { id: sys_ioctl [ 16], common_pid: evolution-addre [ 8571] } hitcount: 1
814 { id: sys_ioctl [ 16], 813 { id: sys_ioctl [ 16], common_pid: gmain [ 3003] } hitcount: 1
815 { id: sys_ioctl [ 16], 814 { id: sys_ioctl [ 16], common_pid: gmain [ 2781] } hitcount: 1
816 { id: sys_ioctl [ 16], 815 { id: sys_ioctl [ 16], common_pid: gmain [ 2829] } hitcount: 1
817 { id: sys_ioctl [ 16], 816 { id: sys_ioctl [ 16], common_pid: bash [ 8726] } hitcount: 1
818 { id: sys_ioctl [ 16], 817 { id: sys_ioctl [ 16], common_pid: bash [ 8508] } hitcount: 1
819 { id: sys_ioctl [ 16], 818 { id: sys_ioctl [ 16], common_pid: gmain [ 2970] } hitcount: 1
820 { id: sys_ioctl [ 16], 819 { id: sys_ioctl [ 16], common_pid: gmain [ 2768] } hitcount: 1
821 . 820 .
822 . 821 .
823 . 822 .
824 { id: sys_ioctl [ 16], 823 { id: sys_ioctl [ 16], common_pid: pool [ 8559] } hitcount: 45
825 { id: sys_ioctl [ 16], 824 { id: sys_ioctl [ 16], common_pid: pool [ 8555] } hitcount: 48
826 { id: sys_ioctl [ 16], 825 { id: sys_ioctl [ 16], common_pid: pool [ 8551] } hitcount: 48
827 { id: sys_ioctl [ 16], 826 { id: sys_ioctl [ 16], common_pid: avahi-daemon [ 896] } hitcount: 66
828 { id: sys_ioctl [ 16], 827 { id: sys_ioctl [ 16], common_pid: Xorg [ 1267] } hitcount: 26674
829 { id: sys_ioctl [ 16], 828 { id: sys_ioctl [ 16], common_pid: compiz [ 2994] } hitcount: 73443
830 829
831 Totals: 830 Totals:
832 Hits: 101162 831 Hits: 101162
833 Entries: 103 832 Entries: 103
834 Dropped: 0 833 Dropped: 0
835 834
836 The above output shows that 'compiz' and 'Xo 835 The above output shows that 'compiz' and 'Xorg' are far and away
837 the heaviest ioctl callers (which might lead 836 the heaviest ioctl callers (which might lead to questions about
838 whether they really need to be making all th 837 whether they really need to be making all those calls and to
839 possible avenues for further investigation.) 838 possible avenues for further investigation.)
840 839
841 The compound key examples used a key and a s 840 The compound key examples used a key and a sum value (hitcount) to
842 sort the output, but we can just as easily u 841 sort the output, but we can just as easily use two keys instead.
843 Here's an example where we use a compound ke 842 Here's an example where we use a compound key composed of the the
844 common_pid and size event fields. Sorting w 843 common_pid and size event fields. Sorting with pid as the primary
845 key and 'size' as the secondary key allows u 844 key and 'size' as the secondary key allows us to display an
846 ordered summary of the recvfrom sizes, with 845 ordered summary of the recvfrom sizes, with counts, received by
847 each process:: 846 each process::
848 847
849 # echo 'hist:key=common_pid.execname,size: 848 # echo 'hist:key=common_pid.execname,size:val=hitcount:sort=common_pid,size' > \
850 /sys/kernel/tracing/events/syscalls !! 849 /sys/kernel/debug/tracing/events/syscalls/sys_enter_recvfrom/trigger
851 850
852 # cat /sys/kernel/tracing/events/syscalls/ !! 851 # cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_recvfrom/hist
853 # trigger info: hist:keys=common_pid.execn 852 # trigger info: hist:keys=common_pid.execname,size:vals=hitcount:sort=common_pid.execname,size:size=2048 [active]
854 853
855 { common_pid: smbd [ 784] 854 { common_pid: smbd [ 784], size: 4 } hitcount: 1
856 { common_pid: dnsmasq [ 1412] 855 { common_pid: dnsmasq [ 1412], size: 4096 } hitcount: 672
857 { common_pid: postgres [ 1796] 856 { common_pid: postgres [ 1796], size: 1000 } hitcount: 6
858 { common_pid: postgres [ 1867] 857 { common_pid: postgres [ 1867], size: 1000 } hitcount: 10
859 { common_pid: bamfdaemon [ 2787] 858 { common_pid: bamfdaemon [ 2787], size: 28 } hitcount: 2
860 { common_pid: bamfdaemon [ 2787] 859 { common_pid: bamfdaemon [ 2787], size: 14360 } hitcount: 1
861 { common_pid: compiz [ 2994] 860 { common_pid: compiz [ 2994], size: 8 } hitcount: 1
862 { common_pid: compiz [ 2994] 861 { common_pid: compiz [ 2994], size: 20 } hitcount: 11
863 { common_pid: gnome-terminal [ 3199] 862 { common_pid: gnome-terminal [ 3199], size: 4 } hitcount: 2
864 { common_pid: firefox [ 8817] 863 { common_pid: firefox [ 8817], size: 4 } hitcount: 1
865 { common_pid: firefox [ 8817] 864 { common_pid: firefox [ 8817], size: 8 } hitcount: 5
866 { common_pid: firefox [ 8817] 865 { common_pid: firefox [ 8817], size: 588 } hitcount: 2
867 { common_pid: firefox [ 8817] 866 { common_pid: firefox [ 8817], size: 628 } hitcount: 1
868 { common_pid: firefox [ 8817] 867 { common_pid: firefox [ 8817], size: 6944 } hitcount: 1
869 { common_pid: firefox [ 8817] 868 { common_pid: firefox [ 8817], size: 408880 } hitcount: 2
870 { common_pid: firefox [ 8822] 869 { common_pid: firefox [ 8822], size: 8 } hitcount: 2
871 { common_pid: firefox [ 8822] 870 { common_pid: firefox [ 8822], size: 160 } hitcount: 2
872 { common_pid: firefox [ 8822] 871 { common_pid: firefox [ 8822], size: 320 } hitcount: 2
873 { common_pid: firefox [ 8822] 872 { common_pid: firefox [ 8822], size: 352 } hitcount: 1
874 . 873 .
875 . 874 .
876 . 875 .
877 { common_pid: pool [ 8923] 876 { common_pid: pool [ 8923], size: 1960 } hitcount: 10
878 { common_pid: pool [ 8923] 877 { common_pid: pool [ 8923], size: 2048 } hitcount: 10
879 { common_pid: pool [ 8924] 878 { common_pid: pool [ 8924], size: 1960 } hitcount: 10
880 { common_pid: pool [ 8924] 879 { common_pid: pool [ 8924], size: 2048 } hitcount: 10
881 { common_pid: pool [ 8928] 880 { common_pid: pool [ 8928], size: 1964 } hitcount: 4
882 { common_pid: pool [ 8928] 881 { common_pid: pool [ 8928], size: 1965 } hitcount: 2
883 { common_pid: pool [ 8928] 882 { common_pid: pool [ 8928], size: 2048 } hitcount: 6
884 { common_pid: pool [ 8929] 883 { common_pid: pool [ 8929], size: 1982 } hitcount: 1
885 { common_pid: pool [ 8929] 884 { common_pid: pool [ 8929], size: 2048 } hitcount: 1
886 885
887 Totals: 886 Totals:
888 Hits: 2016 887 Hits: 2016
889 Entries: 224 888 Entries: 224
890 Dropped: 0 889 Dropped: 0
891 890
892 The above example also illustrates the fact 891 The above example also illustrates the fact that although a compound
893 key is treated as a single entity for hashin 892 key is treated as a single entity for hashing purposes, the sub-keys
894 it's composed of can be accessed independent 893 it's composed of can be accessed independently.
895 894
896 The next example uses a string field as the 895 The next example uses a string field as the hash key and
897 demonstrates how you can manually pause and 896 demonstrates how you can manually pause and continue a hist trigger.
898 In this example, we'll aggregate fork counts 897 In this example, we'll aggregate fork counts and don't expect a
899 large number of entries in the hash table, s 898 large number of entries in the hash table, so we'll drop it to a
900 much smaller number, say 256:: 899 much smaller number, say 256::
901 900
902 # echo 'hist:key=child_comm:val=hitcount:s 901 # echo 'hist:key=child_comm:val=hitcount:size=256' > \
903 /sys/kernel/tracing/events/sched/sc !! 902 /sys/kernel/debug/tracing/events/sched/sched_process_fork/trigger
904 903
905 # cat /sys/kernel/tracing/events/sched/sch !! 904 # cat /sys/kernel/debug/tracing/events/sched/sched_process_fork/hist
906 # trigger info: hist:keys=child_comm:vals= 905 # trigger info: hist:keys=child_comm:vals=hitcount:sort=hitcount:size=256 [active]
907 906
908 { child_comm: dconf worker 907 { child_comm: dconf worker } hitcount: 1
909 { child_comm: ibus-daemon 908 { child_comm: ibus-daemon } hitcount: 1
910 { child_comm: whoopsie 909 { child_comm: whoopsie } hitcount: 1
911 { child_comm: smbd 910 { child_comm: smbd } hitcount: 1
912 { child_comm: gdbus 911 { child_comm: gdbus } hitcount: 1
913 { child_comm: kthreadd 912 { child_comm: kthreadd } hitcount: 1
914 { child_comm: dconf worker 913 { child_comm: dconf worker } hitcount: 1
915 { child_comm: evolution-alarm 914 { child_comm: evolution-alarm } hitcount: 2
916 { child_comm: Socket Thread 915 { child_comm: Socket Thread } hitcount: 2
917 { child_comm: postgres 916 { child_comm: postgres } hitcount: 2
918 { child_comm: bash 917 { child_comm: bash } hitcount: 3
919 { child_comm: compiz 918 { child_comm: compiz } hitcount: 3
920 { child_comm: evolution-sourc 919 { child_comm: evolution-sourc } hitcount: 4
921 { child_comm: dhclient 920 { child_comm: dhclient } hitcount: 4
922 { child_comm: pool 921 { child_comm: pool } hitcount: 5
923 { child_comm: nm-dispatcher.a 922 { child_comm: nm-dispatcher.a } hitcount: 8
924 { child_comm: firefox 923 { child_comm: firefox } hitcount: 8
925 { child_comm: dbus-daemon 924 { child_comm: dbus-daemon } hitcount: 8
926 { child_comm: glib-pacrunner 925 { child_comm: glib-pacrunner } hitcount: 10
927 { child_comm: evolution 926 { child_comm: evolution } hitcount: 23
928 927
929 Totals: 928 Totals:
930 Hits: 89 929 Hits: 89
931 Entries: 20 930 Entries: 20
932 Dropped: 0 931 Dropped: 0
933 932
934 If we want to pause the hist trigger, we can 933 If we want to pause the hist trigger, we can simply append :pause to
935 the command that started the trigger. Notic 934 the command that started the trigger. Notice that the trigger info
936 displays as [paused]:: 935 displays as [paused]::
937 936
938 # echo 'hist:key=child_comm:val=hitcount:s 937 # echo 'hist:key=child_comm:val=hitcount:size=256:pause' >> \
939 /sys/kernel/tracing/events/sched/sc !! 938 /sys/kernel/debug/tracing/events/sched/sched_process_fork/trigger
940 939
941 # cat /sys/kernel/tracing/events/sched/sch !! 940 # cat /sys/kernel/debug/tracing/events/sched/sched_process_fork/hist
942 # trigger info: hist:keys=child_comm:vals= 941 # trigger info: hist:keys=child_comm:vals=hitcount:sort=hitcount:size=256 [paused]
943 942
944 { child_comm: dconf worker 943 { child_comm: dconf worker } hitcount: 1
945 { child_comm: kthreadd 944 { child_comm: kthreadd } hitcount: 1
946 { child_comm: dconf worker 945 { child_comm: dconf worker } hitcount: 1
947 { child_comm: gdbus 946 { child_comm: gdbus } hitcount: 1
948 { child_comm: ibus-daemon 947 { child_comm: ibus-daemon } hitcount: 1
949 { child_comm: Socket Thread 948 { child_comm: Socket Thread } hitcount: 2
950 { child_comm: evolution-alarm 949 { child_comm: evolution-alarm } hitcount: 2
951 { child_comm: smbd 950 { child_comm: smbd } hitcount: 2
952 { child_comm: bash 951 { child_comm: bash } hitcount: 3
953 { child_comm: whoopsie 952 { child_comm: whoopsie } hitcount: 3
954 { child_comm: compiz 953 { child_comm: compiz } hitcount: 3
955 { child_comm: evolution-sourc 954 { child_comm: evolution-sourc } hitcount: 4
956 { child_comm: pool 955 { child_comm: pool } hitcount: 5
957 { child_comm: postgres 956 { child_comm: postgres } hitcount: 6
958 { child_comm: firefox 957 { child_comm: firefox } hitcount: 8
959 { child_comm: dhclient 958 { child_comm: dhclient } hitcount: 10
960 { child_comm: emacs 959 { child_comm: emacs } hitcount: 12
961 { child_comm: dbus-daemon 960 { child_comm: dbus-daemon } hitcount: 20
962 { child_comm: nm-dispatcher.a 961 { child_comm: nm-dispatcher.a } hitcount: 20
963 { child_comm: evolution 962 { child_comm: evolution } hitcount: 35
964 { child_comm: glib-pacrunner 963 { child_comm: glib-pacrunner } hitcount: 59
965 964
966 Totals: 965 Totals:
967 Hits: 199 966 Hits: 199
968 Entries: 21 967 Entries: 21
969 Dropped: 0 968 Dropped: 0
970 969
971 To manually continue having the trigger aggr 970 To manually continue having the trigger aggregate events, append
972 :cont instead. Notice that the trigger info 971 :cont instead. Notice that the trigger info displays as [active]
973 again, and the data has changed:: 972 again, and the data has changed::
974 973
975 # echo 'hist:key=child_comm:val=hitcount:s 974 # echo 'hist:key=child_comm:val=hitcount:size=256:cont' >> \
976 /sys/kernel/tracing/events/sched/sc !! 975 /sys/kernel/debug/tracing/events/sched/sched_process_fork/trigger
977 976
978 # cat /sys/kernel/tracing/events/sched/sch !! 977 # cat /sys/kernel/debug/tracing/events/sched/sched_process_fork/hist
979 # trigger info: hist:keys=child_comm:vals= 978 # trigger info: hist:keys=child_comm:vals=hitcount:sort=hitcount:size=256 [active]
980 979
981 { child_comm: dconf worker 980 { child_comm: dconf worker } hitcount: 1
982 { child_comm: dconf worker 981 { child_comm: dconf worker } hitcount: 1
983 { child_comm: kthreadd 982 { child_comm: kthreadd } hitcount: 1
984 { child_comm: gdbus 983 { child_comm: gdbus } hitcount: 1
985 { child_comm: ibus-daemon 984 { child_comm: ibus-daemon } hitcount: 1
986 { child_comm: Socket Thread 985 { child_comm: Socket Thread } hitcount: 2
987 { child_comm: evolution-alarm 986 { child_comm: evolution-alarm } hitcount: 2
988 { child_comm: smbd 987 { child_comm: smbd } hitcount: 2
989 { child_comm: whoopsie 988 { child_comm: whoopsie } hitcount: 3
990 { child_comm: compiz 989 { child_comm: compiz } hitcount: 3
991 { child_comm: evolution-sourc 990 { child_comm: evolution-sourc } hitcount: 4
992 { child_comm: bash 991 { child_comm: bash } hitcount: 5
993 { child_comm: pool 992 { child_comm: pool } hitcount: 5
994 { child_comm: postgres 993 { child_comm: postgres } hitcount: 6
995 { child_comm: firefox 994 { child_comm: firefox } hitcount: 8
996 { child_comm: dhclient 995 { child_comm: dhclient } hitcount: 11
997 { child_comm: emacs 996 { child_comm: emacs } hitcount: 12
998 { child_comm: dbus-daemon 997 { child_comm: dbus-daemon } hitcount: 22
999 { child_comm: nm-dispatcher.a 998 { child_comm: nm-dispatcher.a } hitcount: 22
1000 { child_comm: evolution 999 { child_comm: evolution } hitcount: 35
1001 { child_comm: glib-pacrunner 1000 { child_comm: glib-pacrunner } hitcount: 59
1002 1001
1003 Totals: 1002 Totals:
1004 Hits: 206 1003 Hits: 206
1005 Entries: 21 1004 Entries: 21
1006 Dropped: 0 1005 Dropped: 0
1007 1006
1008 The previous example showed how to start an 1007 The previous example showed how to start and stop a hist trigger by
1009 appending 'pause' and 'continue' to the his 1008 appending 'pause' and 'continue' to the hist trigger command. A
1010 hist trigger can also be started in a pause 1009 hist trigger can also be started in a paused state by initially
1011 starting the trigger with ':pause' appended 1010 starting the trigger with ':pause' appended. This allows you to
1012 start the trigger only when you're ready to 1011 start the trigger only when you're ready to start collecting data
1013 and not before. For example, you could sta 1012 and not before. For example, you could start the trigger in a
1014 paused state, then unpause it and do someth 1013 paused state, then unpause it and do something you want to measure,
1015 then pause the trigger again when done. 1014 then pause the trigger again when done.
1016 1015
1017 Of course, doing this manually can be diffi 1016 Of course, doing this manually can be difficult and error-prone, but
1018 it is possible to automatically start and s 1017 it is possible to automatically start and stop a hist trigger based
1019 on some condition, via the enable_hist and 1018 on some condition, via the enable_hist and disable_hist triggers.
1020 1019
1021 For example, suppose we wanted to take a lo 1020 For example, suppose we wanted to take a look at the relative
1022 weights in terms of skb length for each cal 1021 weights in terms of skb length for each callpath that leads to a
1023 netif_receive_skb event when downloading a 1022 netif_receive_skb event when downloading a decent-sized file using
1024 wget. 1023 wget.
1025 1024
1026 First we set up an initially paused stacktr 1025 First we set up an initially paused stacktrace trigger on the
1027 netif_receive_skb event:: 1026 netif_receive_skb event::
1028 1027
1029 # echo 'hist:key=common_stacktrace:vals=l !! 1028 # echo 'hist:key=stacktrace:vals=len:pause' > \
1030 /sys/kernel/tracing/events/net/net !! 1029 /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger
1031 1030
1032 Next, we set up an 'enable_hist' trigger on 1031 Next, we set up an 'enable_hist' trigger on the sched_process_exec
1033 event, with an 'if filename==/usr/bin/wget' 1032 event, with an 'if filename==/usr/bin/wget' filter. The effect of
1034 this new trigger is that it will 'unpause' 1033 this new trigger is that it will 'unpause' the hist trigger we just
1035 set up on netif_receive_skb if and only if 1034 set up on netif_receive_skb if and only if it sees a
1036 sched_process_exec event with a filename of 1035 sched_process_exec event with a filename of '/usr/bin/wget'. When
1037 that happens, all netif_receive_skb events 1036 that happens, all netif_receive_skb events are aggregated into a
1038 hash table keyed on stacktrace:: 1037 hash table keyed on stacktrace::
1039 1038
1040 # echo 'enable_hist:net:netif_receive_skb 1039 # echo 'enable_hist:net:netif_receive_skb if filename==/usr/bin/wget' > \
1041 /sys/kernel/tracing/events/sched/s !! 1040 /sys/kernel/debug/tracing/events/sched/sched_process_exec/trigger
1042 1041
1043 The aggregation continues until the netif_r 1042 The aggregation continues until the netif_receive_skb is paused
1044 again, which is what the following disable_ 1043 again, which is what the following disable_hist event does by
1045 creating a similar setup on the sched_proce 1044 creating a similar setup on the sched_process_exit event, using the
1046 filter 'comm==wget':: 1045 filter 'comm==wget'::
1047 1046
1048 # echo 'disable_hist:net:netif_receive_sk 1047 # echo 'disable_hist:net:netif_receive_skb if comm==wget' > \
1049 /sys/kernel/tracing/events/sched/s !! 1048 /sys/kernel/debug/tracing/events/sched/sched_process_exit/trigger
1050 1049
1051 Whenever a process exits and the comm field 1050 Whenever a process exits and the comm field of the disable_hist
1052 trigger filter matches 'comm==wget', the ne 1051 trigger filter matches 'comm==wget', the netif_receive_skb hist
1053 trigger is disabled. 1052 trigger is disabled.
1054 1053
1055 The overall effect is that netif_receive_sk 1054 The overall effect is that netif_receive_skb events are aggregated
1056 into the hash table for only the duration o 1055 into the hash table for only the duration of the wget. Executing a
1057 wget command and then listing the 'hist' fi 1056 wget command and then listing the 'hist' file will display the
1058 output generated by the wget command:: 1057 output generated by the wget command::
1059 1058
1060 $ wget https://www.kernel.org/pub/linux/k 1059 $ wget https://www.kernel.org/pub/linux/kernel/v3.x/patch-3.19.xz
1061 1060
1062 # cat /sys/kernel/tracing/events/net/neti !! 1061 # cat /sys/kernel/debug/tracing/events/net/netif_receive_skb/hist
1063 # trigger info: hist:keys=common_stacktra !! 1062 # trigger info: hist:keys=stacktrace:vals=len:sort=hitcount:size=2048 [paused]
1064 1063
1065 { common_stacktrace: !! 1064 { stacktrace:
1066 __netif_receive_skb_core+0x46d/0x990 1065 __netif_receive_skb_core+0x46d/0x990
1067 __netif_receive_skb+0x18/0x60 1066 __netif_receive_skb+0x18/0x60
1068 netif_receive_skb_internal+0x23/0x90 1067 netif_receive_skb_internal+0x23/0x90
1069 napi_gro_receive+0xc8/0x100 1068 napi_gro_receive+0xc8/0x100
1070 ieee80211_deliver_skb+0xd6/0x270 [ma 1069 ieee80211_deliver_skb+0xd6/0x270 [mac80211]
1071 ieee80211_rx_handlers+0xccf/0x22f0 [ 1070 ieee80211_rx_handlers+0xccf/0x22f0 [mac80211]
1072 ieee80211_prepare_and_rx_handle+0x4e 1071 ieee80211_prepare_and_rx_handle+0x4e7/0xc40 [mac80211]
1073 ieee80211_rx+0x31d/0x900 [mac80211] 1072 ieee80211_rx+0x31d/0x900 [mac80211]
1074 iwlagn_rx_reply_rx+0x3db/0x6f0 [iwld 1073 iwlagn_rx_reply_rx+0x3db/0x6f0 [iwldvm]
1075 iwl_rx_dispatch+0x8e/0xf0 [iwldvm] 1074 iwl_rx_dispatch+0x8e/0xf0 [iwldvm]
1076 iwl_pcie_irq_handler+0xe3c/0x12f0 [i 1075 iwl_pcie_irq_handler+0xe3c/0x12f0 [iwlwifi]
1077 irq_thread_fn+0x20/0x50 1076 irq_thread_fn+0x20/0x50
1078 irq_thread+0x11f/0x150 1077 irq_thread+0x11f/0x150
1079 kthread+0xd2/0xf0 1078 kthread+0xd2/0xf0
1080 ret_from_fork+0x42/0x70 1079 ret_from_fork+0x42/0x70
1081 } hitcount: 85 len: 28884 1080 } hitcount: 85 len: 28884
1082 { common_stacktrace: !! 1081 { stacktrace:
1083 __netif_receive_skb_core+0x46d/0x990 1082 __netif_receive_skb_core+0x46d/0x990
1084 __netif_receive_skb+0x18/0x60 1083 __netif_receive_skb+0x18/0x60
1085 netif_receive_skb_internal+0x23/0x90 1084 netif_receive_skb_internal+0x23/0x90
1086 napi_gro_complete+0xa4/0xe0 1085 napi_gro_complete+0xa4/0xe0
1087 dev_gro_receive+0x23a/0x360 1086 dev_gro_receive+0x23a/0x360
1088 napi_gro_receive+0x30/0x100 1087 napi_gro_receive+0x30/0x100
1089 ieee80211_deliver_skb+0xd6/0x270 [ma 1088 ieee80211_deliver_skb+0xd6/0x270 [mac80211]
1090 ieee80211_rx_handlers+0xccf/0x22f0 [ 1089 ieee80211_rx_handlers+0xccf/0x22f0 [mac80211]
1091 ieee80211_prepare_and_rx_handle+0x4e 1090 ieee80211_prepare_and_rx_handle+0x4e7/0xc40 [mac80211]
1092 ieee80211_rx+0x31d/0x900 [mac80211] 1091 ieee80211_rx+0x31d/0x900 [mac80211]
1093 iwlagn_rx_reply_rx+0x3db/0x6f0 [iwld 1092 iwlagn_rx_reply_rx+0x3db/0x6f0 [iwldvm]
1094 iwl_rx_dispatch+0x8e/0xf0 [iwldvm] 1093 iwl_rx_dispatch+0x8e/0xf0 [iwldvm]
1095 iwl_pcie_irq_handler+0xe3c/0x12f0 [i 1094 iwl_pcie_irq_handler+0xe3c/0x12f0 [iwlwifi]
1096 irq_thread_fn+0x20/0x50 1095 irq_thread_fn+0x20/0x50
1097 irq_thread+0x11f/0x150 1096 irq_thread+0x11f/0x150
1098 kthread+0xd2/0xf0 1097 kthread+0xd2/0xf0
1099 } hitcount: 98 len: 664329 1098 } hitcount: 98 len: 664329
1100 { common_stacktrace: !! 1099 { stacktrace:
1101 __netif_receive_skb_core+0x46d/0x990 1100 __netif_receive_skb_core+0x46d/0x990
1102 __netif_receive_skb+0x18/0x60 1101 __netif_receive_skb+0x18/0x60
1103 process_backlog+0xa8/0x150 1102 process_backlog+0xa8/0x150
1104 net_rx_action+0x15d/0x340 1103 net_rx_action+0x15d/0x340
1105 __do_softirq+0x114/0x2c0 1104 __do_softirq+0x114/0x2c0
1106 do_softirq_own_stack+0x1c/0x30 1105 do_softirq_own_stack+0x1c/0x30
1107 do_softirq+0x65/0x70 1106 do_softirq+0x65/0x70
1108 __local_bh_enable_ip+0xb5/0xc0 1107 __local_bh_enable_ip+0xb5/0xc0
1109 ip_finish_output+0x1f4/0x840 1108 ip_finish_output+0x1f4/0x840
1110 ip_output+0x6b/0xc0 1109 ip_output+0x6b/0xc0
1111 ip_local_out_sk+0x31/0x40 1110 ip_local_out_sk+0x31/0x40
1112 ip_send_skb+0x1a/0x50 1111 ip_send_skb+0x1a/0x50
1113 udp_send_skb+0x173/0x2a0 1112 udp_send_skb+0x173/0x2a0
1114 udp_sendmsg+0x2bf/0x9f0 1113 udp_sendmsg+0x2bf/0x9f0
1115 inet_sendmsg+0x64/0xa0 1114 inet_sendmsg+0x64/0xa0
1116 sock_sendmsg+0x3d/0x50 1115 sock_sendmsg+0x3d/0x50
1117 } hitcount: 115 len: 13030 1116 } hitcount: 115 len: 13030
1118 { common_stacktrace: !! 1117 { stacktrace:
1119 __netif_receive_skb_core+0x46d/0x990 1118 __netif_receive_skb_core+0x46d/0x990
1120 __netif_receive_skb+0x18/0x60 1119 __netif_receive_skb+0x18/0x60
1121 netif_receive_skb_internal+0x23/0x90 1120 netif_receive_skb_internal+0x23/0x90
1122 napi_gro_complete+0xa4/0xe0 1121 napi_gro_complete+0xa4/0xe0
1123 napi_gro_flush+0x6d/0x90 1122 napi_gro_flush+0x6d/0x90
1124 iwl_pcie_irq_handler+0x92a/0x12f0 [i 1123 iwl_pcie_irq_handler+0x92a/0x12f0 [iwlwifi]
1125 irq_thread_fn+0x20/0x50 1124 irq_thread_fn+0x20/0x50
1126 irq_thread+0x11f/0x150 1125 irq_thread+0x11f/0x150
1127 kthread+0xd2/0xf0 1126 kthread+0xd2/0xf0
1128 ret_from_fork+0x42/0x70 1127 ret_from_fork+0x42/0x70
1129 } hitcount: 934 len: 5512212 1128 } hitcount: 934 len: 5512212
1130 1129
1131 Totals: 1130 Totals:
1132 Hits: 1232 1131 Hits: 1232
1133 Entries: 4 1132 Entries: 4
1134 Dropped: 0 1133 Dropped: 0
1135 1134
1136 The above shows all the netif_receive_skb c 1135 The above shows all the netif_receive_skb callpaths and their total
1137 lengths for the duration of the wget comman 1136 lengths for the duration of the wget command.
1138 1137
1139 The 'clear' hist trigger param can be used 1138 The 'clear' hist trigger param can be used to clear the hash table.
1140 Suppose we wanted to try another run of the 1139 Suppose we wanted to try another run of the previous example but
1141 this time also wanted to see the complete l 1140 this time also wanted to see the complete list of events that went
1142 into the histogram. In order to avoid havi 1141 into the histogram. In order to avoid having to set everything up
1143 again, we can just clear the histogram firs 1142 again, we can just clear the histogram first::
1144 1143
1145 # echo 'hist:key=common_stacktrace:vals=l !! 1144 # echo 'hist:key=stacktrace:vals=len:clear' >> \
1146 /sys/kernel/tracing/events/net/net !! 1145 /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger
1147 1146
1148 Just to verify that it is in fact cleared, 1147 Just to verify that it is in fact cleared, here's what we now see in
1149 the hist file:: 1148 the hist file::
1150 1149
1151 # cat /sys/kernel/tracing/events/net/neti !! 1150 # cat /sys/kernel/debug/tracing/events/net/netif_receive_skb/hist
1152 # trigger info: hist:keys=common_stacktra !! 1151 # trigger info: hist:keys=stacktrace:vals=len:sort=hitcount:size=2048 [paused]
1153 1152
1154 Totals: 1153 Totals:
1155 Hits: 0 1154 Hits: 0
1156 Entries: 0 1155 Entries: 0
1157 Dropped: 0 1156 Dropped: 0
1158 1157
1159 Since we want to see the detailed list of e 1158 Since we want to see the detailed list of every netif_receive_skb
1160 event occurring during the new run, which a 1159 event occurring during the new run, which are in fact the same
1161 events being aggregated into the hash table 1160 events being aggregated into the hash table, we add some additional
1162 'enable_event' events to the triggering sch 1161 'enable_event' events to the triggering sched_process_exec and
1163 sched_process_exit events as such:: 1162 sched_process_exit events as such::
1164 1163
1165 # echo 'enable_event:net:netif_receive_sk 1164 # echo 'enable_event:net:netif_receive_skb if filename==/usr/bin/wget' > \
1166 /sys/kernel/tracing/events/sched/s !! 1165 /sys/kernel/debug/tracing/events/sched/sched_process_exec/trigger
1167 1166
1168 # echo 'disable_event:net:netif_receive_s 1167 # echo 'disable_event:net:netif_receive_skb if comm==wget' > \
1169 /sys/kernel/tracing/events/sched/s !! 1168 /sys/kernel/debug/tracing/events/sched/sched_process_exit/trigger
1170 1169
1171 If you read the trigger files for the sched 1170 If you read the trigger files for the sched_process_exec and
1172 sched_process_exit triggers, you should see 1171 sched_process_exit triggers, you should see two triggers for each:
1173 one enabling/disabling the hist aggregation 1172 one enabling/disabling the hist aggregation and the other
1174 enabling/disabling the logging of events:: 1173 enabling/disabling the logging of events::
1175 1174
1176 # cat /sys/kernel/tracing/events/sched/sc !! 1175 # cat /sys/kernel/debug/tracing/events/sched/sched_process_exec/trigger
1177 enable_event:net:netif_receive_skb:unlimi 1176 enable_event:net:netif_receive_skb:unlimited if filename==/usr/bin/wget
1178 enable_hist:net:netif_receive_skb:unlimit 1177 enable_hist:net:netif_receive_skb:unlimited if filename==/usr/bin/wget
1179 1178
1180 # cat /sys/kernel/tracing/events/sched/sc !! 1179 # cat /sys/kernel/debug/tracing/events/sched/sched_process_exit/trigger
1181 enable_event:net:netif_receive_skb:unlimi 1180 enable_event:net:netif_receive_skb:unlimited if comm==wget
1182 disable_hist:net:netif_receive_skb:unlimi 1181 disable_hist:net:netif_receive_skb:unlimited if comm==wget
1183 1182
1184 In other words, whenever either of the sche 1183 In other words, whenever either of the sched_process_exec or
1185 sched_process_exit events is hit and matche 1184 sched_process_exit events is hit and matches 'wget', it enables or
1186 disables both the histogram and the event l 1185 disables both the histogram and the event log, and what you end up
1187 with is a hash table and set of events just 1186 with is a hash table and set of events just covering the specified
1188 duration. Run the wget command again:: 1187 duration. Run the wget command again::
1189 1188
1190 $ wget https://www.kernel.org/pub/linux/k 1189 $ wget https://www.kernel.org/pub/linux/kernel/v3.x/patch-3.19.xz
1191 1190
1192 Displaying the 'hist' file should show some 1191 Displaying the 'hist' file should show something similar to what you
1193 saw in the last run, but this time you shou 1192 saw in the last run, but this time you should also see the
1194 individual events in the trace file:: 1193 individual events in the trace file::
1195 1194
1196 # cat /sys/kernel/tracing/trace !! 1195 # cat /sys/kernel/debug/tracing/trace
1197 1196
1198 # tracer: nop 1197 # tracer: nop
1199 # 1198 #
1200 # entries-in-buffer/entries-written: 183/ 1199 # entries-in-buffer/entries-written: 183/1426 #P:4
1201 # 1200 #
1202 # _-----=> i 1201 # _-----=> irqs-off
1203 # / _----=> n 1202 # / _----=> need-resched
1204 # | / _---=> h 1203 # | / _---=> hardirq/softirq
1205 # || / _--=> p 1204 # || / _--=> preempt-depth
1206 # ||| / de 1205 # ||| / delay
1207 # TASK-PID CPU# |||| TIME 1206 # TASK-PID CPU# |||| TIMESTAMP FUNCTION
1208 # | | | |||| | 1207 # | | | |||| | |
1209 wget-15108 [000] ..s1 31769.6 1208 wget-15108 [000] ..s1 31769.606929: netif_receive_skb: dev=lo skbaddr=ffff88009c353100 len=60
1210 wget-15108 [000] ..s1 31769.6 1209 wget-15108 [000] ..s1 31769.606999: netif_receive_skb: dev=lo skbaddr=ffff88009c353200 len=60
1211 dnsmasq-1382 [000] ..s1 31769.6 1210 dnsmasq-1382 [000] ..s1 31769.677652: netif_receive_skb: dev=lo skbaddr=ffff88009c352b00 len=130
1212 dnsmasq-1382 [000] ..s1 31769.6 1211 dnsmasq-1382 [000] ..s1 31769.685917: netif_receive_skb: dev=lo skbaddr=ffff88009c352200 len=138
1213 ##### CPU 2 buffer started #### 1212 ##### CPU 2 buffer started ####
1214 irq/29-iwlwifi-559 [002] ..s. 31772.0 1213 irq/29-iwlwifi-559 [002] ..s. 31772.031529: netif_receive_skb: dev=wlan0 skbaddr=ffff88009d433d00 len=2948
1215 irq/29-iwlwifi-559 [002] ..s. 31772.0 1214 irq/29-iwlwifi-559 [002] ..s. 31772.031572: netif_receive_skb: dev=wlan0 skbaddr=ffff88009d432200 len=1500
1216 irq/29-iwlwifi-559 [002] ..s. 31772.0 1215 irq/29-iwlwifi-559 [002] ..s. 31772.032196: netif_receive_skb: dev=wlan0 skbaddr=ffff88009d433100 len=2948
1217 irq/29-iwlwifi-559 [002] ..s. 31772.0 1216 irq/29-iwlwifi-559 [002] ..s. 31772.032761: netif_receive_skb: dev=wlan0 skbaddr=ffff88009d433000 len=2948
1218 irq/29-iwlwifi-559 [002] ..s. 31772.0 1217 irq/29-iwlwifi-559 [002] ..s. 31772.033220: netif_receive_skb: dev=wlan0 skbaddr=ffff88009d432e00 len=1500
1219 . 1218 .
1220 . 1219 .
1221 . 1220 .
1222 1221
1223 The following example demonstrates how mult 1222 The following example demonstrates how multiple hist triggers can be
1224 attached to a given event. This capability 1223 attached to a given event. This capability can be useful for
1225 creating a set of different summaries deriv 1224 creating a set of different summaries derived from the same set of
1226 events, or for comparing the effects of dif 1225 events, or for comparing the effects of different filters, among
1227 other things:: 1226 other things::
1228 1227
1229 # echo 'hist:keys=skbaddr.hex:vals=len if 1228 # echo 'hist:keys=skbaddr.hex:vals=len if len < 0' >> \
1230 /sys/kernel/tracing/events/net/net !! 1229 /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger
1231 # echo 'hist:keys=skbaddr.hex:vals=len if 1230 # echo 'hist:keys=skbaddr.hex:vals=len if len > 4096' >> \
1232 /sys/kernel/tracing/events/net/net !! 1231 /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger
1233 # echo 'hist:keys=skbaddr.hex:vals=len if 1232 # echo 'hist:keys=skbaddr.hex:vals=len if len == 256' >> \
1234 /sys/kernel/tracing/events/net/net !! 1233 /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger
1235 # echo 'hist:keys=skbaddr.hex:vals=len' > 1234 # echo 'hist:keys=skbaddr.hex:vals=len' >> \
1236 /sys/kernel/tracing/events/net/net !! 1235 /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger
1237 # echo 'hist:keys=len:vals=common_preempt 1236 # echo 'hist:keys=len:vals=common_preempt_count' >> \
1238 /sys/kernel/tracing/events/net/net !! 1237 /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger
1239 1238
1240 The above set of commands create four trigg 1239 The above set of commands create four triggers differing only in
1241 their filters, along with a completely diff 1240 their filters, along with a completely different though fairly
1242 nonsensical trigger. Note that in order to 1241 nonsensical trigger. Note that in order to append multiple hist
1243 triggers to the same file, you should use t 1242 triggers to the same file, you should use the '>>' operator to
1244 append them ('>' will also add the new hist 1243 append them ('>' will also add the new hist trigger, but will remove
1245 any existing hist triggers beforehand). 1244 any existing hist triggers beforehand).
1246 1245
1247 Displaying the contents of the 'hist' file 1246 Displaying the contents of the 'hist' file for the event shows the
1248 contents of all five histograms:: 1247 contents of all five histograms::
1249 1248
1250 # cat /sys/kernel/tracing/events/net/neti !! 1249 # cat /sys/kernel/debug/tracing/events/net/netif_receive_skb/hist
1251 1250
1252 # event histogram 1251 # event histogram
1253 # 1252 #
1254 # trigger info: hist:keys=len:vals=hitcou 1253 # trigger info: hist:keys=len:vals=hitcount,common_preempt_count:sort=hitcount:size=2048 [active]
1255 # 1254 #
1256 1255
1257 { len: 176 } hitcount: 1 1256 { len: 176 } hitcount: 1 common_preempt_count: 0
1258 { len: 223 } hitcount: 1 1257 { len: 223 } hitcount: 1 common_preempt_count: 0
1259 { len: 4854 } hitcount: 1 1258 { len: 4854 } hitcount: 1 common_preempt_count: 0
1260 { len: 395 } hitcount: 1 1259 { len: 395 } hitcount: 1 common_preempt_count: 0
1261 { len: 177 } hitcount: 1 1260 { len: 177 } hitcount: 1 common_preempt_count: 0
1262 { len: 446 } hitcount: 1 1261 { len: 446 } hitcount: 1 common_preempt_count: 0
1263 { len: 1601 } hitcount: 1 1262 { len: 1601 } hitcount: 1 common_preempt_count: 0
1264 . 1263 .
1265 . 1264 .
1266 . 1265 .
1267 { len: 1280 } hitcount: 66 1266 { len: 1280 } hitcount: 66 common_preempt_count: 0
1268 { len: 116 } hitcount: 81 1267 { len: 116 } hitcount: 81 common_preempt_count: 40
1269 { len: 708 } hitcount: 112 1268 { len: 708 } hitcount: 112 common_preempt_count: 0
1270 { len: 46 } hitcount: 221 1269 { len: 46 } hitcount: 221 common_preempt_count: 0
1271 { len: 1264 } hitcount: 458 1270 { len: 1264 } hitcount: 458 common_preempt_count: 0
1272 1271
1273 Totals: 1272 Totals:
1274 Hits: 1428 1273 Hits: 1428
1275 Entries: 147 1274 Entries: 147
1276 Dropped: 0 1275 Dropped: 0
1277 1276
1278 1277
1279 # event histogram 1278 # event histogram
1280 # 1279 #
1281 # trigger info: hist:keys=skbaddr.hex:val 1280 # trigger info: hist:keys=skbaddr.hex:vals=hitcount,len:sort=hitcount:size=2048 [active]
1282 # 1281 #
1283 1282
1284 { skbaddr: ffff8800baee5e00 } hitcount: 1283 { skbaddr: ffff8800baee5e00 } hitcount: 1 len: 130
1285 { skbaddr: ffff88005f3d5600 } hitcount: 1284 { skbaddr: ffff88005f3d5600 } hitcount: 1 len: 1280
1286 { skbaddr: ffff88005f3d4900 } hitcount: 1285 { skbaddr: ffff88005f3d4900 } hitcount: 1 len: 1280
1287 { skbaddr: ffff88009fed6300 } hitcount: 1286 { skbaddr: ffff88009fed6300 } hitcount: 1 len: 115
1288 { skbaddr: ffff88009fe0ad00 } hitcount: 1287 { skbaddr: ffff88009fe0ad00 } hitcount: 1 len: 115
1289 { skbaddr: ffff88008cdb1900 } hitcount: 1288 { skbaddr: ffff88008cdb1900 } hitcount: 1 len: 46
1290 { skbaddr: ffff880064b5ef00 } hitcount: 1289 { skbaddr: ffff880064b5ef00 } hitcount: 1 len: 118
1291 { skbaddr: ffff880044e3c700 } hitcount: 1290 { skbaddr: ffff880044e3c700 } hitcount: 1 len: 60
1292 { skbaddr: ffff880100065900 } hitcount: 1291 { skbaddr: ffff880100065900 } hitcount: 1 len: 46
1293 { skbaddr: ffff8800d46bd500 } hitcount: 1292 { skbaddr: ffff8800d46bd500 } hitcount: 1 len: 116
1294 { skbaddr: ffff88005f3d5f00 } hitcount: 1293 { skbaddr: ffff88005f3d5f00 } hitcount: 1 len: 1280
1295 { skbaddr: ffff880100064700 } hitcount: 1294 { skbaddr: ffff880100064700 } hitcount: 1 len: 365
1296 { skbaddr: ffff8800badb6f00 } hitcount: 1295 { skbaddr: ffff8800badb6f00 } hitcount: 1 len: 60
1297 . 1296 .
1298 . 1297 .
1299 . 1298 .
1300 { skbaddr: ffff88009fe0be00 } hitcount: 1299 { skbaddr: ffff88009fe0be00 } hitcount: 27 len: 24677
1301 { skbaddr: ffff88009fe0a400 } hitcount: 1300 { skbaddr: ffff88009fe0a400 } hitcount: 27 len: 23052
1302 { skbaddr: ffff88009fe0b700 } hitcount: 1301 { skbaddr: ffff88009fe0b700 } hitcount: 31 len: 25589
1303 { skbaddr: ffff88009fe0b600 } hitcount: 1302 { skbaddr: ffff88009fe0b600 } hitcount: 32 len: 27326
1304 { skbaddr: ffff88006a462800 } hitcount: 1303 { skbaddr: ffff88006a462800 } hitcount: 68 len: 71678
1305 { skbaddr: ffff88006a463700 } hitcount: 1304 { skbaddr: ffff88006a463700 } hitcount: 70 len: 72678
1306 { skbaddr: ffff88006a462b00 } hitcount: 1305 { skbaddr: ffff88006a462b00 } hitcount: 71 len: 77589
1307 { skbaddr: ffff88006a463600 } hitcount: 1306 { skbaddr: ffff88006a463600 } hitcount: 73 len: 71307
1308 { skbaddr: ffff88006a462200 } hitcount: 1307 { skbaddr: ffff88006a462200 } hitcount: 81 len: 81032
1309 1308
1310 Totals: 1309 Totals:
1311 Hits: 1451 1310 Hits: 1451
1312 Entries: 318 1311 Entries: 318
1313 Dropped: 0 1312 Dropped: 0
1314 1313
1315 1314
1316 # event histogram 1315 # event histogram
1317 # 1316 #
1318 # trigger info: hist:keys=skbaddr.hex:val 1317 # trigger info: hist:keys=skbaddr.hex:vals=hitcount,len:sort=hitcount:size=2048 if len == 256 [active]
1319 # 1318 #
1320 1319
1321 1320
1322 Totals: 1321 Totals:
1323 Hits: 0 1322 Hits: 0
1324 Entries: 0 1323 Entries: 0
1325 Dropped: 0 1324 Dropped: 0
1326 1325
1327 1326
1328 # event histogram 1327 # event histogram
1329 # 1328 #
1330 # trigger info: hist:keys=skbaddr.hex:val 1329 # trigger info: hist:keys=skbaddr.hex:vals=hitcount,len:sort=hitcount:size=2048 if len > 4096 [active]
1331 # 1330 #
1332 1331
1333 { skbaddr: ffff88009fd2c300 } hitcount: 1332 { skbaddr: ffff88009fd2c300 } hitcount: 1 len: 7212
1334 { skbaddr: ffff8800d2bcce00 } hitcount: 1333 { skbaddr: ffff8800d2bcce00 } hitcount: 1 len: 7212
1335 { skbaddr: ffff8800d2bcd700 } hitcount: 1334 { skbaddr: ffff8800d2bcd700 } hitcount: 1 len: 7212
1336 { skbaddr: ffff8800d2bcda00 } hitcount: 1335 { skbaddr: ffff8800d2bcda00 } hitcount: 1 len: 21492
1337 { skbaddr: ffff8800ae2e2d00 } hitcount: 1336 { skbaddr: ffff8800ae2e2d00 } hitcount: 1 len: 7212
1338 { skbaddr: ffff8800d2bcdb00 } hitcount: 1337 { skbaddr: ffff8800d2bcdb00 } hitcount: 1 len: 7212
1339 { skbaddr: ffff88006a4df500 } hitcount: 1338 { skbaddr: ffff88006a4df500 } hitcount: 1 len: 4854
1340 { skbaddr: ffff88008ce47b00 } hitcount: 1339 { skbaddr: ffff88008ce47b00 } hitcount: 1 len: 18636
1341 { skbaddr: ffff8800ae2e2200 } hitcount: 1340 { skbaddr: ffff8800ae2e2200 } hitcount: 1 len: 12924
1342 { skbaddr: ffff88005f3e1000 } hitcount: 1341 { skbaddr: ffff88005f3e1000 } hitcount: 1 len: 4356
1343 { skbaddr: ffff8800d2bcdc00 } hitcount: 1342 { skbaddr: ffff8800d2bcdc00 } hitcount: 2 len: 24420
1344 { skbaddr: ffff8800d2bcc200 } hitcount: 1343 { skbaddr: ffff8800d2bcc200 } hitcount: 2 len: 12996
1345 1344
1346 Totals: 1345 Totals:
1347 Hits: 14 1346 Hits: 14
1348 Entries: 12 1347 Entries: 12
1349 Dropped: 0 1348 Dropped: 0
1350 1349
1351 1350
1352 # event histogram 1351 # event histogram
1353 # 1352 #
1354 # trigger info: hist:keys=skbaddr.hex:val 1353 # trigger info: hist:keys=skbaddr.hex:vals=hitcount,len:sort=hitcount:size=2048 if len < 0 [active]
1355 # 1354 #
1356 1355
1357 1356
1358 Totals: 1357 Totals:
1359 Hits: 0 1358 Hits: 0
1360 Entries: 0 1359 Entries: 0
1361 Dropped: 0 1360 Dropped: 0
1362 1361
1363 Named triggers can be used to have triggers 1362 Named triggers can be used to have triggers share a common set of
1364 histogram data. This capability is mostly 1363 histogram data. This capability is mostly useful for combining the
1365 output of events generated by tracepoints c 1364 output of events generated by tracepoints contained inside inline
1366 functions, but names can be used in a hist 1365 functions, but names can be used in a hist trigger on any event.
1367 For example, these two triggers when hit wi 1366 For example, these two triggers when hit will update the same 'len'
1368 field in the shared 'foo' histogram data:: 1367 field in the shared 'foo' histogram data::
1369 1368
1370 # echo 'hist:name=foo:keys=skbaddr.hex:va 1369 # echo 'hist:name=foo:keys=skbaddr.hex:vals=len' > \
1371 /sys/kernel/tracing/events/net/net !! 1370 /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger
1372 # echo 'hist:name=foo:keys=skbaddr.hex:va 1371 # echo 'hist:name=foo:keys=skbaddr.hex:vals=len' > \
1373 /sys/kernel/tracing/events/net/net !! 1372 /sys/kernel/debug/tracing/events/net/netif_rx/trigger
1374 1373
1375 You can see that they're updating common hi 1374 You can see that they're updating common histogram data by reading
1376 each event's hist files at the same time:: 1375 each event's hist files at the same time::
1377 1376
1378 # cat /sys/kernel/tracing/events/net/neti !! 1377 # cat /sys/kernel/debug/tracing/events/net/netif_receive_skb/hist;
1379 cat /sys/kernel/tracing/events/net/neti !! 1378 cat /sys/kernel/debug/tracing/events/net/netif_rx/hist
1380 1379
1381 # event histogram 1380 # event histogram
1382 # 1381 #
1383 # trigger info: hist:name=foo:keys=skbadd 1382 # trigger info: hist:name=foo:keys=skbaddr.hex:vals=hitcount,len:sort=hitcount:size=2048 [active]
1384 # 1383 #
1385 1384
1386 { skbaddr: ffff88000ad53500 } hitcount: 1385 { skbaddr: ffff88000ad53500 } hitcount: 1 len: 46
1387 { skbaddr: ffff8800af5a1500 } hitcount: 1386 { skbaddr: ffff8800af5a1500 } hitcount: 1 len: 76
1388 { skbaddr: ffff8800d62a1900 } hitcount: 1387 { skbaddr: ffff8800d62a1900 } hitcount: 1 len: 46
1389 { skbaddr: ffff8800d2bccb00 } hitcount: 1388 { skbaddr: ffff8800d2bccb00 } hitcount: 1 len: 468
1390 { skbaddr: ffff8800d3c69900 } hitcount: 1389 { skbaddr: ffff8800d3c69900 } hitcount: 1 len: 46
1391 { skbaddr: ffff88009ff09100 } hitcount: 1390 { skbaddr: ffff88009ff09100 } hitcount: 1 len: 52
1392 { skbaddr: ffff88010f13ab00 } hitcount: 1391 { skbaddr: ffff88010f13ab00 } hitcount: 1 len: 168
1393 { skbaddr: ffff88006a54f400 } hitcount: 1392 { skbaddr: ffff88006a54f400 } hitcount: 1 len: 46
1394 { skbaddr: ffff8800d2bcc500 } hitcount: 1393 { skbaddr: ffff8800d2bcc500 } hitcount: 1 len: 260
1395 { skbaddr: ffff880064505000 } hitcount: 1394 { skbaddr: ffff880064505000 } hitcount: 1 len: 46
1396 { skbaddr: ffff8800baf24e00 } hitcount: 1395 { skbaddr: ffff8800baf24e00 } hitcount: 1 len: 32
1397 { skbaddr: ffff88009fe0ad00 } hitcount: 1396 { skbaddr: ffff88009fe0ad00 } hitcount: 1 len: 46
1398 { skbaddr: ffff8800d3edff00 } hitcount: 1397 { skbaddr: ffff8800d3edff00 } hitcount: 1 len: 44
1399 { skbaddr: ffff88009fe0b400 } hitcount: 1398 { skbaddr: ffff88009fe0b400 } hitcount: 1 len: 168
1400 { skbaddr: ffff8800a1c55a00 } hitcount: 1399 { skbaddr: ffff8800a1c55a00 } hitcount: 1 len: 40
1401 { skbaddr: ffff8800d2bcd100 } hitcount: 1400 { skbaddr: ffff8800d2bcd100 } hitcount: 1 len: 40
1402 { skbaddr: ffff880064505f00 } hitcount: 1401 { skbaddr: ffff880064505f00 } hitcount: 1 len: 174
1403 { skbaddr: ffff8800a8bff200 } hitcount: 1402 { skbaddr: ffff8800a8bff200 } hitcount: 1 len: 160
1404 { skbaddr: ffff880044e3cc00 } hitcount: 1403 { skbaddr: ffff880044e3cc00 } hitcount: 1 len: 76
1405 { skbaddr: ffff8800a8bfe700 } hitcount: 1404 { skbaddr: ffff8800a8bfe700 } hitcount: 1 len: 46
1406 { skbaddr: ffff8800d2bcdc00 } hitcount: 1405 { skbaddr: ffff8800d2bcdc00 } hitcount: 1 len: 32
1407 { skbaddr: ffff8800a1f64800 } hitcount: 1406 { skbaddr: ffff8800a1f64800 } hitcount: 1 len: 46
1408 { skbaddr: ffff8800d2bcde00 } hitcount: 1407 { skbaddr: ffff8800d2bcde00 } hitcount: 1 len: 988
1409 { skbaddr: ffff88006a5dea00 } hitcount: 1408 { skbaddr: ffff88006a5dea00 } hitcount: 1 len: 46
1410 { skbaddr: ffff88002e37a200 } hitcount: 1409 { skbaddr: ffff88002e37a200 } hitcount: 1 len: 44
1411 { skbaddr: ffff8800a1f32c00 } hitcount: 1410 { skbaddr: ffff8800a1f32c00 } hitcount: 2 len: 676
1412 { skbaddr: ffff88000ad52600 } hitcount: 1411 { skbaddr: ffff88000ad52600 } hitcount: 2 len: 107
1413 { skbaddr: ffff8800a1f91e00 } hitcount: 1412 { skbaddr: ffff8800a1f91e00 } hitcount: 2 len: 92
1414 { skbaddr: ffff8800af5a0200 } hitcount: 1413 { skbaddr: ffff8800af5a0200 } hitcount: 2 len: 142
1415 { skbaddr: ffff8800d2bcc600 } hitcount: 1414 { skbaddr: ffff8800d2bcc600 } hitcount: 2 len: 220
1416 { skbaddr: ffff8800ba36f500 } hitcount: 1415 { skbaddr: ffff8800ba36f500 } hitcount: 2 len: 92
1417 { skbaddr: ffff8800d021f800 } hitcount: 1416 { skbaddr: ffff8800d021f800 } hitcount: 2 len: 92
1418 { skbaddr: ffff8800a1f33600 } hitcount: 1417 { skbaddr: ffff8800a1f33600 } hitcount: 2 len: 675
1419 { skbaddr: ffff8800a8bfff00 } hitcount: 1418 { skbaddr: ffff8800a8bfff00 } hitcount: 3 len: 138
1420 { skbaddr: ffff8800d62a1300 } hitcount: 1419 { skbaddr: ffff8800d62a1300 } hitcount: 3 len: 138
1421 { skbaddr: ffff88002e37a100 } hitcount: 1420 { skbaddr: ffff88002e37a100 } hitcount: 4 len: 184
1422 { skbaddr: ffff880064504400 } hitcount: 1421 { skbaddr: ffff880064504400 } hitcount: 4 len: 184
1423 { skbaddr: ffff8800a8bfec00 } hitcount: 1422 { skbaddr: ffff8800a8bfec00 } hitcount: 4 len: 184
1424 { skbaddr: ffff88000ad53700 } hitcount: 1423 { skbaddr: ffff88000ad53700 } hitcount: 5 len: 230
1425 { skbaddr: ffff8800d2bcdb00 } hitcount: 1424 { skbaddr: ffff8800d2bcdb00 } hitcount: 5 len: 196
1426 { skbaddr: ffff8800a1f90000 } hitcount: 1425 { skbaddr: ffff8800a1f90000 } hitcount: 6 len: 276
1427 { skbaddr: ffff88006a54f900 } hitcount: 1426 { skbaddr: ffff88006a54f900 } hitcount: 6 len: 276
1428 1427
1429 Totals: 1428 Totals:
1430 Hits: 81 1429 Hits: 81
1431 Entries: 42 1430 Entries: 42
1432 Dropped: 0 1431 Dropped: 0
1433 # event histogram 1432 # event histogram
1434 # 1433 #
1435 # trigger info: hist:name=foo:keys=skbadd 1434 # trigger info: hist:name=foo:keys=skbaddr.hex:vals=hitcount,len:sort=hitcount:size=2048 [active]
1436 # 1435 #
1437 1436
1438 { skbaddr: ffff88000ad53500 } hitcount: 1437 { skbaddr: ffff88000ad53500 } hitcount: 1 len: 46
1439 { skbaddr: ffff8800af5a1500 } hitcount: 1438 { skbaddr: ffff8800af5a1500 } hitcount: 1 len: 76
1440 { skbaddr: ffff8800d62a1900 } hitcount: 1439 { skbaddr: ffff8800d62a1900 } hitcount: 1 len: 46
1441 { skbaddr: ffff8800d2bccb00 } hitcount: 1440 { skbaddr: ffff8800d2bccb00 } hitcount: 1 len: 468
1442 { skbaddr: ffff8800d3c69900 } hitcount: 1441 { skbaddr: ffff8800d3c69900 } hitcount: 1 len: 46
1443 { skbaddr: ffff88009ff09100 } hitcount: 1442 { skbaddr: ffff88009ff09100 } hitcount: 1 len: 52
1444 { skbaddr: ffff88010f13ab00 } hitcount: 1443 { skbaddr: ffff88010f13ab00 } hitcount: 1 len: 168
1445 { skbaddr: ffff88006a54f400 } hitcount: 1444 { skbaddr: ffff88006a54f400 } hitcount: 1 len: 46
1446 { skbaddr: ffff8800d2bcc500 } hitcount: 1445 { skbaddr: ffff8800d2bcc500 } hitcount: 1 len: 260
1447 { skbaddr: ffff880064505000 } hitcount: 1446 { skbaddr: ffff880064505000 } hitcount: 1 len: 46
1448 { skbaddr: ffff8800baf24e00 } hitcount: 1447 { skbaddr: ffff8800baf24e00 } hitcount: 1 len: 32
1449 { skbaddr: ffff88009fe0ad00 } hitcount: 1448 { skbaddr: ffff88009fe0ad00 } hitcount: 1 len: 46
1450 { skbaddr: ffff8800d3edff00 } hitcount: 1449 { skbaddr: ffff8800d3edff00 } hitcount: 1 len: 44
1451 { skbaddr: ffff88009fe0b400 } hitcount: 1450 { skbaddr: ffff88009fe0b400 } hitcount: 1 len: 168
1452 { skbaddr: ffff8800a1c55a00 } hitcount: 1451 { skbaddr: ffff8800a1c55a00 } hitcount: 1 len: 40
1453 { skbaddr: ffff8800d2bcd100 } hitcount: 1452 { skbaddr: ffff8800d2bcd100 } hitcount: 1 len: 40
1454 { skbaddr: ffff880064505f00 } hitcount: 1453 { skbaddr: ffff880064505f00 } hitcount: 1 len: 174
1455 { skbaddr: ffff8800a8bff200 } hitcount: 1454 { skbaddr: ffff8800a8bff200 } hitcount: 1 len: 160
1456 { skbaddr: ffff880044e3cc00 } hitcount: 1455 { skbaddr: ffff880044e3cc00 } hitcount: 1 len: 76
1457 { skbaddr: ffff8800a8bfe700 } hitcount: 1456 { skbaddr: ffff8800a8bfe700 } hitcount: 1 len: 46
1458 { skbaddr: ffff8800d2bcdc00 } hitcount: 1457 { skbaddr: ffff8800d2bcdc00 } hitcount: 1 len: 32
1459 { skbaddr: ffff8800a1f64800 } hitcount: 1458 { skbaddr: ffff8800a1f64800 } hitcount: 1 len: 46
1460 { skbaddr: ffff8800d2bcde00 } hitcount: 1459 { skbaddr: ffff8800d2bcde00 } hitcount: 1 len: 988
1461 { skbaddr: ffff88006a5dea00 } hitcount: 1460 { skbaddr: ffff88006a5dea00 } hitcount: 1 len: 46
1462 { skbaddr: ffff88002e37a200 } hitcount: 1461 { skbaddr: ffff88002e37a200 } hitcount: 1 len: 44
1463 { skbaddr: ffff8800a1f32c00 } hitcount: 1462 { skbaddr: ffff8800a1f32c00 } hitcount: 2 len: 676
1464 { skbaddr: ffff88000ad52600 } hitcount: 1463 { skbaddr: ffff88000ad52600 } hitcount: 2 len: 107
1465 { skbaddr: ffff8800a1f91e00 } hitcount: 1464 { skbaddr: ffff8800a1f91e00 } hitcount: 2 len: 92
1466 { skbaddr: ffff8800af5a0200 } hitcount: 1465 { skbaddr: ffff8800af5a0200 } hitcount: 2 len: 142
1467 { skbaddr: ffff8800d2bcc600 } hitcount: 1466 { skbaddr: ffff8800d2bcc600 } hitcount: 2 len: 220
1468 { skbaddr: ffff8800ba36f500 } hitcount: 1467 { skbaddr: ffff8800ba36f500 } hitcount: 2 len: 92
1469 { skbaddr: ffff8800d021f800 } hitcount: 1468 { skbaddr: ffff8800d021f800 } hitcount: 2 len: 92
1470 { skbaddr: ffff8800a1f33600 } hitcount: 1469 { skbaddr: ffff8800a1f33600 } hitcount: 2 len: 675
1471 { skbaddr: ffff8800a8bfff00 } hitcount: 1470 { skbaddr: ffff8800a8bfff00 } hitcount: 3 len: 138
1472 { skbaddr: ffff8800d62a1300 } hitcount: 1471 { skbaddr: ffff8800d62a1300 } hitcount: 3 len: 138
1473 { skbaddr: ffff88002e37a100 } hitcount: 1472 { skbaddr: ffff88002e37a100 } hitcount: 4 len: 184
1474 { skbaddr: ffff880064504400 } hitcount: 1473 { skbaddr: ffff880064504400 } hitcount: 4 len: 184
1475 { skbaddr: ffff8800a8bfec00 } hitcount: 1474 { skbaddr: ffff8800a8bfec00 } hitcount: 4 len: 184
1476 { skbaddr: ffff88000ad53700 } hitcount: 1475 { skbaddr: ffff88000ad53700 } hitcount: 5 len: 230
1477 { skbaddr: ffff8800d2bcdb00 } hitcount: 1476 { skbaddr: ffff8800d2bcdb00 } hitcount: 5 len: 196
1478 { skbaddr: ffff8800a1f90000 } hitcount: 1477 { skbaddr: ffff8800a1f90000 } hitcount: 6 len: 276
1479 { skbaddr: ffff88006a54f900 } hitcount: 1478 { skbaddr: ffff88006a54f900 } hitcount: 6 len: 276
1480 1479
1481 Totals: 1480 Totals:
1482 Hits: 81 1481 Hits: 81
1483 Entries: 42 1482 Entries: 42
1484 Dropped: 0 1483 Dropped: 0
1485 1484
1486 And here's an example that shows how to com 1485 And here's an example that shows how to combine histogram data from
1487 any two events even if they don't share any 1486 any two events even if they don't share any 'compatible' fields
1488 other than 'hitcount' and 'common_stacktrac !! 1487 other than 'hitcount' and 'stacktrace'. These commands create a
1489 couple of triggers named 'bar' using those 1488 couple of triggers named 'bar' using those fields::
1490 1489
1491 # echo 'hist:name=bar:key=common_stacktra !! 1490 # echo 'hist:name=bar:key=stacktrace:val=hitcount' > \
1492 /sys/kernel/tracing/events/sched/s !! 1491 /sys/kernel/debug/tracing/events/sched/sched_process_fork/trigger
1493 # echo 'hist:name=bar:key=common_stacktra !! 1492 # echo 'hist:name=bar:key=stacktrace:val=hitcount' > \
1494 /sys/kernel/tracing/events/net/neti !! 1493 /sys/kernel/debug/tracing/events/net/netif_rx/trigger
1495 1494
1496 And displaying the output of either shows s 1495 And displaying the output of either shows some interesting if
1497 somewhat confusing output:: 1496 somewhat confusing output::
1498 1497
1499 # cat /sys/kernel/tracing/events/sched/sc !! 1498 # cat /sys/kernel/debug/tracing/events/sched/sched_process_fork/hist
1500 # cat /sys/kernel/tracing/events/net/neti !! 1499 # cat /sys/kernel/debug/tracing/events/net/netif_rx/hist
1501 1500
1502 # event histogram 1501 # event histogram
1503 # 1502 #
1504 # trigger info: hist:name=bar:keys=common !! 1503 # trigger info: hist:name=bar:keys=stacktrace:vals=hitcount:sort=hitcount:size=2048 [active]
1505 # 1504 #
1506 1505
1507 { common_stacktrace: !! 1506 { stacktrace:
1508 kernel_clone+0x18e/0x330 1507 kernel_clone+0x18e/0x330
1509 kernel_thread+0x29/0x30 1508 kernel_thread+0x29/0x30
1510 kthreadd+0x154/0x1b0 1509 kthreadd+0x154/0x1b0
1511 ret_from_fork+0x3f/0x70 1510 ret_from_fork+0x3f/0x70
1512 } hitcount: 1 1511 } hitcount: 1
1513 { common_stacktrace: !! 1512 { stacktrace:
1514 netif_rx_internal+0xb2/0xd0 1513 netif_rx_internal+0xb2/0xd0
1515 netif_rx_ni+0x20/0x70 1514 netif_rx_ni+0x20/0x70
1516 dev_loopback_xmit+0xaa/0xd0 1515 dev_loopback_xmit+0xaa/0xd0
1517 ip_mc_output+0x126/0x240 1516 ip_mc_output+0x126/0x240
1518 ip_local_out_sk+0x31/0x40 1517 ip_local_out_sk+0x31/0x40
1519 igmp_send_report+0x1e9/0x230 1518 igmp_send_report+0x1e9/0x230
1520 igmp_timer_expire+0xe9/0x120 1519 igmp_timer_expire+0xe9/0x120
1521 call_timer_fn+0x39/0xf0 1520 call_timer_fn+0x39/0xf0
1522 run_timer_softirq+0x1e1/0x290 1521 run_timer_softirq+0x1e1/0x290
1523 __do_softirq+0xfd/0x290 1522 __do_softirq+0xfd/0x290
1524 irq_exit+0x98/0xb0 1523 irq_exit+0x98/0xb0
1525 smp_apic_timer_interrupt+0x4a/0x 1524 smp_apic_timer_interrupt+0x4a/0x60
1526 apic_timer_interrupt+0x6d/0x80 1525 apic_timer_interrupt+0x6d/0x80
1527 cpuidle_enter+0x17/0x20 1526 cpuidle_enter+0x17/0x20
1528 call_cpuidle+0x3b/0x60 1527 call_cpuidle+0x3b/0x60
1529 cpu_startup_entry+0x22d/0x310 1528 cpu_startup_entry+0x22d/0x310
1530 } hitcount: 1 1529 } hitcount: 1
1531 { common_stacktrace: !! 1530 { stacktrace:
1532 netif_rx_internal+0xb2/0xd0 1531 netif_rx_internal+0xb2/0xd0
1533 netif_rx_ni+0x20/0x70 1532 netif_rx_ni+0x20/0x70
1534 dev_loopback_xmit+0xaa/0xd0 1533 dev_loopback_xmit+0xaa/0xd0
1535 ip_mc_output+0x17f/0x240 1534 ip_mc_output+0x17f/0x240
1536 ip_local_out_sk+0x31/0x40 1535 ip_local_out_sk+0x31/0x40
1537 ip_send_skb+0x1a/0x50 1536 ip_send_skb+0x1a/0x50
1538 udp_send_skb+0x13e/0x270 1537 udp_send_skb+0x13e/0x270
1539 udp_sendmsg+0x2bf/0x980 1538 udp_sendmsg+0x2bf/0x980
1540 inet_sendmsg+0x67/0xa0 1539 inet_sendmsg+0x67/0xa0
1541 sock_sendmsg+0x38/0x50 1540 sock_sendmsg+0x38/0x50
1542 SYSC_sendto+0xef/0x170 1541 SYSC_sendto+0xef/0x170
1543 SyS_sendto+0xe/0x10 1542 SyS_sendto+0xe/0x10
1544 entry_SYSCALL_64_fastpath+0x12/0 1543 entry_SYSCALL_64_fastpath+0x12/0x6a
1545 } hitcount: 2 1544 } hitcount: 2
1546 { common_stacktrace: !! 1545 { stacktrace:
1547 netif_rx_internal+0xb2/0xd0 1546 netif_rx_internal+0xb2/0xd0
1548 netif_rx+0x1c/0x60 1547 netif_rx+0x1c/0x60
1549 loopback_xmit+0x6c/0xb0 1548 loopback_xmit+0x6c/0xb0
1550 dev_hard_start_xmit+0x219/0x3a0 1549 dev_hard_start_xmit+0x219/0x3a0
1551 __dev_queue_xmit+0x415/0x4f0 1550 __dev_queue_xmit+0x415/0x4f0
1552 dev_queue_xmit_sk+0x13/0x20 1551 dev_queue_xmit_sk+0x13/0x20
1553 ip_finish_output2+0x237/0x340 1552 ip_finish_output2+0x237/0x340
1554 ip_finish_output+0x113/0x1d0 1553 ip_finish_output+0x113/0x1d0
1555 ip_output+0x66/0xc0 1554 ip_output+0x66/0xc0
1556 ip_local_out_sk+0x31/0x40 1555 ip_local_out_sk+0x31/0x40
1557 ip_send_skb+0x1a/0x50 1556 ip_send_skb+0x1a/0x50
1558 udp_send_skb+0x16d/0x270 1557 udp_send_skb+0x16d/0x270
1559 udp_sendmsg+0x2bf/0x980 1558 udp_sendmsg+0x2bf/0x980
1560 inet_sendmsg+0x67/0xa0 1559 inet_sendmsg+0x67/0xa0
1561 sock_sendmsg+0x38/0x50 1560 sock_sendmsg+0x38/0x50
1562 ___sys_sendmsg+0x14e/0x270 1561 ___sys_sendmsg+0x14e/0x270
1563 } hitcount: 76 1562 } hitcount: 76
1564 { common_stacktrace: !! 1563 { stacktrace:
1565 netif_rx_internal+0xb2/0xd0 1564 netif_rx_internal+0xb2/0xd0
1566 netif_rx+0x1c/0x60 1565 netif_rx+0x1c/0x60
1567 loopback_xmit+0x6c/0xb0 1566 loopback_xmit+0x6c/0xb0
1568 dev_hard_start_xmit+0x219/0x3a0 1567 dev_hard_start_xmit+0x219/0x3a0
1569 __dev_queue_xmit+0x415/0x4f0 1568 __dev_queue_xmit+0x415/0x4f0
1570 dev_queue_xmit_sk+0x13/0x20 1569 dev_queue_xmit_sk+0x13/0x20
1571 ip_finish_output2+0x237/0x340 1570 ip_finish_output2+0x237/0x340
1572 ip_finish_output+0x113/0x1d0 1571 ip_finish_output+0x113/0x1d0
1573 ip_output+0x66/0xc0 1572 ip_output+0x66/0xc0
1574 ip_local_out_sk+0x31/0x40 1573 ip_local_out_sk+0x31/0x40
1575 ip_send_skb+0x1a/0x50 1574 ip_send_skb+0x1a/0x50
1576 udp_send_skb+0x16d/0x270 1575 udp_send_skb+0x16d/0x270
1577 udp_sendmsg+0x2bf/0x980 1576 udp_sendmsg+0x2bf/0x980
1578 inet_sendmsg+0x67/0xa0 1577 inet_sendmsg+0x67/0xa0
1579 sock_sendmsg+0x38/0x50 1578 sock_sendmsg+0x38/0x50
1580 ___sys_sendmsg+0x269/0x270 1579 ___sys_sendmsg+0x269/0x270
1581 } hitcount: 77 1580 } hitcount: 77
1582 { common_stacktrace: !! 1581 { stacktrace:
1583 netif_rx_internal+0xb2/0xd0 1582 netif_rx_internal+0xb2/0xd0
1584 netif_rx+0x1c/0x60 1583 netif_rx+0x1c/0x60
1585 loopback_xmit+0x6c/0xb0 1584 loopback_xmit+0x6c/0xb0
1586 dev_hard_start_xmit+0x219/0x3a0 1585 dev_hard_start_xmit+0x219/0x3a0
1587 __dev_queue_xmit+0x415/0x4f0 1586 __dev_queue_xmit+0x415/0x4f0
1588 dev_queue_xmit_sk+0x13/0x20 1587 dev_queue_xmit_sk+0x13/0x20
1589 ip_finish_output2+0x237/0x340 1588 ip_finish_output2+0x237/0x340
1590 ip_finish_output+0x113/0x1d0 1589 ip_finish_output+0x113/0x1d0
1591 ip_output+0x66/0xc0 1590 ip_output+0x66/0xc0
1592 ip_local_out_sk+0x31/0x40 1591 ip_local_out_sk+0x31/0x40
1593 ip_send_skb+0x1a/0x50 1592 ip_send_skb+0x1a/0x50
1594 udp_send_skb+0x16d/0x270 1593 udp_send_skb+0x16d/0x270
1595 udp_sendmsg+0x2bf/0x980 1594 udp_sendmsg+0x2bf/0x980
1596 inet_sendmsg+0x67/0xa0 1595 inet_sendmsg+0x67/0xa0
1597 sock_sendmsg+0x38/0x50 1596 sock_sendmsg+0x38/0x50
1598 SYSC_sendto+0xef/0x170 1597 SYSC_sendto+0xef/0x170
1599 } hitcount: 88 1598 } hitcount: 88
1600 { common_stacktrace: !! 1599 { stacktrace:
1601 kernel_clone+0x18e/0x330 1600 kernel_clone+0x18e/0x330
1602 SyS_clone+0x19/0x20 1601 SyS_clone+0x19/0x20
1603 entry_SYSCALL_64_fastpath+0x12/0 1602 entry_SYSCALL_64_fastpath+0x12/0x6a
1604 } hitcount: 244 1603 } hitcount: 244
1605 1604
1606 Totals: 1605 Totals:
1607 Hits: 489 1606 Hits: 489
1608 Entries: 7 1607 Entries: 7
1609 Dropped: 0 1608 Dropped: 0
1610 1609
1611 2.2 Inter-event hist triggers 1610 2.2 Inter-event hist triggers
1612 ----------------------------- 1611 -----------------------------
1613 1612
1614 Inter-event hist triggers are hist triggers t 1613 Inter-event hist triggers are hist triggers that combine values from
1615 one or more other events and create a histogr 1614 one or more other events and create a histogram using that data. Data
1616 from an inter-event histogram can in turn bec 1615 from an inter-event histogram can in turn become the source for
1617 further combined histograms, thus providing a 1616 further combined histograms, thus providing a chain of related
1618 histograms, which is important for some appli 1617 histograms, which is important for some applications.
1619 1618
1620 The most important example of an inter-event 1619 The most important example of an inter-event quantity that can be used
1621 in this manner is latency, which is simply a 1620 in this manner is latency, which is simply a difference in timestamps
1622 between two events. Although latency is the 1621 between two events. Although latency is the most important
1623 inter-event quantity, note that because the s 1622 inter-event quantity, note that because the support is completely
1624 general across the trace event subsystem, any 1623 general across the trace event subsystem, any event field can be used
1625 in an inter-event quantity. 1624 in an inter-event quantity.
1626 1625
1627 An example of a histogram that combines data 1626 An example of a histogram that combines data from other histograms
1628 into a useful chain would be a 'wakeupswitch 1627 into a useful chain would be a 'wakeupswitch latency' histogram that
1629 combines a 'wakeup latency' histogram and a ' 1628 combines a 'wakeup latency' histogram and a 'switch latency'
1630 histogram. 1629 histogram.
1631 1630
1632 Normally, a hist trigger specification consis 1631 Normally, a hist trigger specification consists of a (possibly
1633 compound) key along with one or more numeric 1632 compound) key along with one or more numeric values, which are
1634 continually updated sums associated with that 1633 continually updated sums associated with that key. A histogram
1635 specification in this case consists of indivi 1634 specification in this case consists of individual key and value
1636 specifications that refer to trace event fiel 1635 specifications that refer to trace event fields associated with a
1637 single event type. 1636 single event type.
1638 1637
1639 The inter-event hist trigger extension allows 1638 The inter-event hist trigger extension allows fields from multiple
1640 events to be referenced and combined into a m 1639 events to be referenced and combined into a multi-event histogram
1641 specification. In support of this overall go 1640 specification. In support of this overall goal, a few enabling
1642 features have been added to the hist trigger 1641 features have been added to the hist trigger support:
1643 1642
1644 - In order to compute an inter-event quanti 1643 - In order to compute an inter-event quantity, a value from one
1645 event needs to saved and then referenced 1644 event needs to saved and then referenced from another event. This
1646 requires the introduction of support for 1645 requires the introduction of support for histogram 'variables'.
1647 1646
1648 - The computation of inter-event quantities 1647 - The computation of inter-event quantities and their combination
1649 require some minimal amount of support fo 1648 require some minimal amount of support for applying simple
1650 expressions to variables (+ and -). 1649 expressions to variables (+ and -).
1651 1650
1652 - A histogram consisting of inter-event qua 1651 - A histogram consisting of inter-event quantities isn't logically a
1653 histogram on either event (so having the 1652 histogram on either event (so having the 'hist' file for either
1654 event host the histogram output doesn't r 1653 event host the histogram output doesn't really make sense). To
1655 address the idea that the histogram is as 1654 address the idea that the histogram is associated with a
1656 combination of events, support is added a 1655 combination of events, support is added allowing the creation of
1657 'synthetic' events that are events derive 1656 'synthetic' events that are events derived from other events.
1658 These synthetic events are full-fledged e 1657 These synthetic events are full-fledged events just like any other
1659 and can be used as such, as for instance 1658 and can be used as such, as for instance to create the
1660 'combination' histograms mentioned previo 1659 'combination' histograms mentioned previously.
1661 1660
1662 - A set of 'actions' can be associated with 1661 - A set of 'actions' can be associated with histogram entries -
1663 these can be used to generate the previou 1662 these can be used to generate the previously mentioned synthetic
1664 events, but can also be used for other pu 1663 events, but can also be used for other purposes, such as for
1665 example saving context when a 'max' laten 1664 example saving context when a 'max' latency has been hit.
1666 1665
1667 - Trace events don't have a 'timestamp' ass 1666 - Trace events don't have a 'timestamp' associated with them, but
1668 there is an implicit timestamp saved alon 1667 there is an implicit timestamp saved along with an event in the
1669 underlying ftrace ring buffer. This time 1668 underlying ftrace ring buffer. This timestamp is now exposed as a
1670 a synthetic field named 'common_timestamp 1669 a synthetic field named 'common_timestamp' which can be used in
1671 histograms as if it were any other event 1670 histograms as if it were any other event field; it isn't an actual
1672 field in the trace format but rather is a 1671 field in the trace format but rather is a synthesized value that
1673 nonetheless can be used as if it were an 1672 nonetheless can be used as if it were an actual field. By default
1674 it is in units of nanoseconds; appending 1673 it is in units of nanoseconds; appending '.usecs' to a
1675 common_timestamp field changes the units 1674 common_timestamp field changes the units to microseconds.
1676 1675
1677 A note on inter-event timestamps: If common_t 1676 A note on inter-event timestamps: If common_timestamp is used in a
1678 histogram, the trace buffer is automatically 1677 histogram, the trace buffer is automatically switched over to using
1679 absolute timestamps and the "global" trace cl 1678 absolute timestamps and the "global" trace clock, in order to avoid
1680 bogus timestamp differences with other clocks 1679 bogus timestamp differences with other clocks that aren't coherent
1681 across CPUs. This can be overridden by speci 1680 across CPUs. This can be overridden by specifying one of the other
1682 trace clocks instead, using the "clock=XXX" h 1681 trace clocks instead, using the "clock=XXX" hist trigger attribute,
1683 where XXX is any of the clocks listed in the 1682 where XXX is any of the clocks listed in the tracing/trace_clock
1684 pseudo-file. 1683 pseudo-file.
1685 1684
1686 These features are described in more detail i 1685 These features are described in more detail in the following sections.
1687 1686
1688 2.2.1 Histogram Variables 1687 2.2.1 Histogram Variables
1689 ------------------------- 1688 -------------------------
1690 1689
1691 Variables are simply named locations used for 1690 Variables are simply named locations used for saving and retrieving
1692 values between matching events. A 'matching' 1691 values between matching events. A 'matching' event is defined as an
1693 event that has a matching key - if a variable 1692 event that has a matching key - if a variable is saved for a histogram
1694 entry corresponding to that key, any subseque 1693 entry corresponding to that key, any subsequent event with a matching
1695 key can access that variable. 1694 key can access that variable.
1696 1695
1697 A variable's value is normally available to a 1696 A variable's value is normally available to any subsequent event until
1698 it is set to something else by a subsequent e 1697 it is set to something else by a subsequent event. The one exception
1699 to that rule is that any variable used in an 1698 to that rule is that any variable used in an expression is essentially
1700 'read-once' - once it's used by an expression 1699 'read-once' - once it's used by an expression in a subsequent event,
1701 it's reset to its 'unset' state, which means 1700 it's reset to its 'unset' state, which means it can't be used again
1702 unless it's set again. This ensures not only 1701 unless it's set again. This ensures not only that an event doesn't
1703 use an uninitialized variable in a calculatio 1702 use an uninitialized variable in a calculation, but that that variable
1704 is used only once and not for any unrelated s 1703 is used only once and not for any unrelated subsequent match.
1705 1704
1706 The basic syntax for saving a variable is to 1705 The basic syntax for saving a variable is to simply prefix a unique
1707 variable name not corresponding to any keywor 1706 variable name not corresponding to any keyword along with an '=' sign
1708 to any event field. 1707 to any event field.
1709 1708
1710 Either keys or values can be saved and retrie 1709 Either keys or values can be saved and retrieved in this way. This
1711 creates a variable named 'ts0' for a histogra 1710 creates a variable named 'ts0' for a histogram entry with the key
1712 'next_pid':: 1711 'next_pid'::
1713 1712
1714 # echo 'hist:keys=next_pid:vals=$ts0:ts0=co 1713 # echo 'hist:keys=next_pid:vals=$ts0:ts0=common_timestamp ... >> \
1715 event/trigger 1714 event/trigger
1716 1715
1717 The ts0 variable can be accessed by any subse 1716 The ts0 variable can be accessed by any subsequent event having the
1718 same pid as 'next_pid'. 1717 same pid as 'next_pid'.
1719 1718
1720 Variable references are formed by prepending 1719 Variable references are formed by prepending the variable name with
1721 the '$' sign. Thus for example, the ts0 vari 1720 the '$' sign. Thus for example, the ts0 variable above would be
1722 referenced as '$ts0' in expressions. 1721 referenced as '$ts0' in expressions.
1723 1722
1724 Because 'vals=' is used, the common_timestamp 1723 Because 'vals=' is used, the common_timestamp variable value above
1725 will also be summed as a normal histogram val 1724 will also be summed as a normal histogram value would (though for a
1726 timestamp it makes little sense). 1725 timestamp it makes little sense).
1727 1726
1728 The below shows that a key value can also be 1727 The below shows that a key value can also be saved in the same way::
1729 1728
1730 # echo 'hist:timer_pid=common_pid:key=timer 1729 # echo 'hist:timer_pid=common_pid:key=timer_pid ...' >> event/trigger
1731 1730
1732 If a variable isn't a key variable or prefixe 1731 If a variable isn't a key variable or prefixed with 'vals=', the
1733 associated event field will be saved in a var 1732 associated event field will be saved in a variable but won't be summed
1734 as a value:: 1733 as a value::
1735 1734
1736 # echo 'hist:keys=next_pid:ts1=common_times 1735 # echo 'hist:keys=next_pid:ts1=common_timestamp ...' >> event/trigger
1737 1736
1738 Multiple variables can be assigned at the sam 1737 Multiple variables can be assigned at the same time. The below would
1739 result in both ts0 and b being created as var 1738 result in both ts0 and b being created as variables, with both
1740 common_timestamp and field1 additionally bein 1739 common_timestamp and field1 additionally being summed as values::
1741 1740
1742 # echo 'hist:keys=pid:vals=$ts0,$b:ts0=comm 1741 # echo 'hist:keys=pid:vals=$ts0,$b:ts0=common_timestamp,b=field1 ...' >> \
1743 event/trigger 1742 event/trigger
1744 1743
1745 Note that variable assignments can appear eit 1744 Note that variable assignments can appear either preceding or
1746 following their use. The command below behav 1745 following their use. The command below behaves identically to the
1747 command above:: 1746 command above::
1748 1747
1749 # echo 'hist:keys=pid:ts0=common_timestamp, 1748 # echo 'hist:keys=pid:ts0=common_timestamp,b=field1:vals=$ts0,$b ...' >> \
1750 event/trigger 1749 event/trigger
1751 1750
1752 Any number of variables not bound to a 'vals= 1751 Any number of variables not bound to a 'vals=' prefix can also be
1753 assigned by simply separating them with colon 1752 assigned by simply separating them with colons. Below is the same
1754 thing but without the values being summed in 1753 thing but without the values being summed in the histogram::
1755 1754
1756 # echo 'hist:keys=pid:ts0=common_timestamp: 1755 # echo 'hist:keys=pid:ts0=common_timestamp:b=field1 ...' >> event/trigger
1757 1756
1758 Variables set as above can be referenced and 1757 Variables set as above can be referenced and used in expressions on
1759 another event. 1758 another event.
1760 1759
1761 For example, here's how a latency can be calc 1760 For example, here's how a latency can be calculated::
1762 1761
1763 # echo 'hist:keys=pid,prio:ts0=common_times 1762 # echo 'hist:keys=pid,prio:ts0=common_timestamp ...' >> event1/trigger
1764 # echo 'hist:keys=next_pid:wakeup_lat=commo 1763 # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp-$ts0 ...' >> event2/trigger
1765 1764
1766 In the first line above, the event's timestam 1765 In the first line above, the event's timestamp is saved into the
1767 variable ts0. In the next line, ts0 is subtr 1766 variable ts0. In the next line, ts0 is subtracted from the second
1768 event's timestamp to produce the latency, whi 1767 event's timestamp to produce the latency, which is then assigned into
1769 yet another variable, 'wakeup_lat'. The hist 1768 yet another variable, 'wakeup_lat'. The hist trigger below in turn
1770 makes use of the wakeup_lat variable to compu 1769 makes use of the wakeup_lat variable to compute a combined latency
1771 using the same key and variable from yet anot 1770 using the same key and variable from yet another event::
1772 1771
1773 # echo 'hist:key=pid:wakeupswitch_lat=$wake 1772 # echo 'hist:key=pid:wakeupswitch_lat=$wakeup_lat+$switchtime_lat ...' >> event3/trigger
1774 1773
1775 Expressions support the use of addition, subt 1774 Expressions support the use of addition, subtraction, multiplication and
1776 division operators (+-\*/). 1775 division operators (+-\*/).
1777 1776
1778 Note if division by zero cannot be detected a 1777 Note if division by zero cannot be detected at parse time (i.e. the
1779 divisor is not a constant), the result will b 1778 divisor is not a constant), the result will be -1.
1780 1779
1781 Numeric constants can also be used directly i 1780 Numeric constants can also be used directly in an expression::
1782 1781
1783 # echo 'hist:keys=next_pid:timestamp_secs=c 1782 # echo 'hist:keys=next_pid:timestamp_secs=common_timestamp/1000000 ...' >> event/trigger
1784 1783
1785 or assigned to a variable and referenced in a 1784 or assigned to a variable and referenced in a subsequent expression::
1786 1785
1787 # echo 'hist:keys=next_pid:us_per_sec=10000 1786 # echo 'hist:keys=next_pid:us_per_sec=1000000 ...' >> event/trigger
1788 # echo 'hist:keys=next_pid:timestamp_secs=c 1787 # echo 'hist:keys=next_pid:timestamp_secs=common_timestamp/$us_per_sec ...' >> event/trigger
1789 1788
1790 Variables can even hold stacktraces, which ar <<
1791 <<
1792 2.2.2 Synthetic Events 1789 2.2.2 Synthetic Events
1793 ---------------------- 1790 ----------------------
1794 1791
1795 Synthetic events are user-defined events gene 1792 Synthetic events are user-defined events generated from hist trigger
1796 variables or fields associated with one or mo 1793 variables or fields associated with one or more other events. Their
1797 purpose is to provide a mechanism for display 1794 purpose is to provide a mechanism for displaying data spanning
1798 multiple events consistent with the existing 1795 multiple events consistent with the existing and already familiar
1799 usage for normal events. 1796 usage for normal events.
1800 1797
1801 To define a synthetic event, the user writes 1798 To define a synthetic event, the user writes a simple specification
1802 consisting of the name of the new event along 1799 consisting of the name of the new event along with one or more
1803 variables and their types, which can be any v 1800 variables and their types, which can be any valid field type,
1804 separated by semicolons, to the tracing/synth 1801 separated by semicolons, to the tracing/synthetic_events file.
1805 1802
1806 See synth_field_size() for available types. 1803 See synth_field_size() for available types.
1807 1804
1808 If field_name contains [n], the field is cons 1805 If field_name contains [n], the field is considered to be a static array.
1809 1806
1810 If field_names contains[] (no subscript), the 1807 If field_names contains[] (no subscript), the field is considered to
1811 be a dynamic array, which will only take as m 1808 be a dynamic array, which will only take as much space in the event as
1812 is required to hold the array. 1809 is required to hold the array.
1813 1810
1814 A string field can be specified using either 1811 A string field can be specified using either the static notation:
1815 1812
1816 char name[32]; 1813 char name[32];
1817 1814
1818 Or the dynamic: 1815 Or the dynamic:
1819 1816
1820 char name[]; 1817 char name[];
1821 1818
1822 The size limit for either is 256. 1819 The size limit for either is 256.
1823 1820
1824 For instance, the following creates a new eve 1821 For instance, the following creates a new event named 'wakeup_latency'
1825 with 3 fields: lat, pid, and prio. Each of t 1822 with 3 fields: lat, pid, and prio. Each of those fields is simply a
1826 variable reference to a variable on another e 1823 variable reference to a variable on another event::
1827 1824
1828 # echo 'wakeup_latency \ 1825 # echo 'wakeup_latency \
1829 u64 lat; \ 1826 u64 lat; \
1830 pid_t pid; \ 1827 pid_t pid; \
1831 int prio' >> \ 1828 int prio' >> \
1832 /sys/kernel/tracing/synthetic_event !! 1829 /sys/kernel/debug/tracing/synthetic_events
1833 1830
1834 Reading the tracing/synthetic_events file lis 1831 Reading the tracing/synthetic_events file lists all the currently
1835 defined synthetic events, in this case the ev 1832 defined synthetic events, in this case the event defined above::
1836 1833
1837 # cat /sys/kernel/tracing/synthetic_events !! 1834 # cat /sys/kernel/debug/tracing/synthetic_events
1838 wakeup_latency u64 lat; pid_t pid; int pr 1835 wakeup_latency u64 lat; pid_t pid; int prio
1839 1836
1840 An existing synthetic event definition can be 1837 An existing synthetic event definition can be removed by prepending
1841 the command that defined it with a '!':: 1838 the command that defined it with a '!'::
1842 1839
1843 # echo '!wakeup_latency u64 lat pid_t pid i 1840 # echo '!wakeup_latency u64 lat pid_t pid int prio' >> \
1844 /sys/kernel/tracing/synthetic_events !! 1841 /sys/kernel/debug/tracing/synthetic_events
1845 1842
1846 At this point, there isn't yet an actual 'wak 1843 At this point, there isn't yet an actual 'wakeup_latency' event
1847 instantiated in the event subsystem - for thi 1844 instantiated in the event subsystem - for this to happen, a 'hist
1848 trigger action' needs to be instantiated and 1845 trigger action' needs to be instantiated and bound to actual fields
1849 and variables defined on other events (see Se 1846 and variables defined on other events (see Section 2.2.3 below on
1850 how that is done using hist trigger 'onmatch' 1847 how that is done using hist trigger 'onmatch' action). Once that is
1851 done, the 'wakeup_latency' synthetic event in 1848 done, the 'wakeup_latency' synthetic event instance is created.
1852 1849
1853 The new event is created under the tracing/ev 1850 The new event is created under the tracing/events/synthetic/ directory
1854 and looks and behaves just like any other eve 1851 and looks and behaves just like any other event::
1855 1852
1856 # ls /sys/kernel/tracing/events/synthetic/w !! 1853 # ls /sys/kernel/debug/tracing/events/synthetic/wakeup_latency
1857 enable filter format hist id tri 1854 enable filter format hist id trigger
1858 1855
1859 A histogram can now be defined for the new sy 1856 A histogram can now be defined for the new synthetic event::
1860 1857
1861 # echo 'hist:keys=pid,prio,lat.log2:sort=la 1858 # echo 'hist:keys=pid,prio,lat.log2:sort=lat' >> \
1862 /sys/kernel/tracing/events/synthetic/ !! 1859 /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/trigger
1863 1860
1864 The above shows the latency "lat" in a power 1861 The above shows the latency "lat" in a power of 2 grouping.
1865 1862
1866 Like any other event, once a histogram is ena 1863 Like any other event, once a histogram is enabled for the event, the
1867 output can be displayed by reading the event' !! 1864 output can be displayed by reading the event's 'hist' file.
1868 1865
1869 # cat /sys/kernel/tracing/events/synthetic/ !! 1866 # cat /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/hist
1870 1867
1871 # event histogram 1868 # event histogram
1872 # 1869 #
1873 # trigger info: hist:keys=pid,prio,lat.log2 1870 # trigger info: hist:keys=pid,prio,lat.log2:vals=hitcount:sort=lat.log2:size=2048 [active]
1874 # 1871 #
1875 1872
1876 { pid: 2035, prio: 9, lat: ~ 1873 { pid: 2035, prio: 9, lat: ~ 2^2 } hitcount: 43
1877 { pid: 2034, prio: 9, lat: ~ 1874 { pid: 2034, prio: 9, lat: ~ 2^2 } hitcount: 60
1878 { pid: 2029, prio: 9, lat: ~ 1875 { pid: 2029, prio: 9, lat: ~ 2^2 } hitcount: 965
1879 { pid: 2034, prio: 120, lat: ~ 1876 { pid: 2034, prio: 120, lat: ~ 2^2 } hitcount: 9
1880 { pid: 2033, prio: 120, lat: ~ 1877 { pid: 2033, prio: 120, lat: ~ 2^2 } hitcount: 5
1881 { pid: 2030, prio: 9, lat: ~ 1878 { pid: 2030, prio: 9, lat: ~ 2^2 } hitcount: 335
1882 { pid: 2030, prio: 120, lat: ~ 1879 { pid: 2030, prio: 120, lat: ~ 2^2 } hitcount: 10
1883 { pid: 2032, prio: 120, lat: ~ 1880 { pid: 2032, prio: 120, lat: ~ 2^2 } hitcount: 1
1884 { pid: 2035, prio: 120, lat: ~ 1881 { pid: 2035, prio: 120, lat: ~ 2^2 } hitcount: 2
1885 { pid: 2031, prio: 9, lat: ~ 1882 { pid: 2031, prio: 9, lat: ~ 2^2 } hitcount: 176
1886 { pid: 2028, prio: 120, lat: ~ 1883 { pid: 2028, prio: 120, lat: ~ 2^2 } hitcount: 15
1887 { pid: 2033, prio: 9, lat: ~ 1884 { pid: 2033, prio: 9, lat: ~ 2^2 } hitcount: 91
1888 { pid: 2032, prio: 9, lat: ~ 1885 { pid: 2032, prio: 9, lat: ~ 2^2 } hitcount: 125
1889 { pid: 2029, prio: 120, lat: ~ 1886 { pid: 2029, prio: 120, lat: ~ 2^2 } hitcount: 4
1890 { pid: 2031, prio: 120, lat: ~ 1887 { pid: 2031, prio: 120, lat: ~ 2^2 } hitcount: 3
1891 { pid: 2029, prio: 120, lat: ~ 1888 { pid: 2029, prio: 120, lat: ~ 2^3 } hitcount: 2
1892 { pid: 2035, prio: 9, lat: ~ 1889 { pid: 2035, prio: 9, lat: ~ 2^3 } hitcount: 41
1893 { pid: 2030, prio: 120, lat: ~ 1890 { pid: 2030, prio: 120, lat: ~ 2^3 } hitcount: 1
1894 { pid: 2032, prio: 9, lat: ~ 1891 { pid: 2032, prio: 9, lat: ~ 2^3 } hitcount: 32
1895 { pid: 2031, prio: 9, lat: ~ 1892 { pid: 2031, prio: 9, lat: ~ 2^3 } hitcount: 44
1896 { pid: 2034, prio: 9, lat: ~ 1893 { pid: 2034, prio: 9, lat: ~ 2^3 } hitcount: 40
1897 { pid: 2030, prio: 9, lat: ~ 1894 { pid: 2030, prio: 9, lat: ~ 2^3 } hitcount: 29
1898 { pid: 2033, prio: 9, lat: ~ 1895 { pid: 2033, prio: 9, lat: ~ 2^3 } hitcount: 31
1899 { pid: 2029, prio: 9, lat: ~ 1896 { pid: 2029, prio: 9, lat: ~ 2^3 } hitcount: 31
1900 { pid: 2028, prio: 120, lat: ~ 1897 { pid: 2028, prio: 120, lat: ~ 2^3 } hitcount: 18
1901 { pid: 2031, prio: 120, lat: ~ 1898 { pid: 2031, prio: 120, lat: ~ 2^3 } hitcount: 2
1902 { pid: 2028, prio: 120, lat: ~ 1899 { pid: 2028, prio: 120, lat: ~ 2^4 } hitcount: 1
1903 { pid: 2029, prio: 9, lat: ~ 1900 { pid: 2029, prio: 9, lat: ~ 2^4 } hitcount: 4
1904 { pid: 2031, prio: 120, lat: ~ 1901 { pid: 2031, prio: 120, lat: ~ 2^7 } hitcount: 1
1905 { pid: 2032, prio: 120, lat: ~ 1902 { pid: 2032, prio: 120, lat: ~ 2^7 } hitcount: 1
1906 1903
1907 Totals: 1904 Totals:
1908 Hits: 2122 1905 Hits: 2122
1909 Entries: 30 1906 Entries: 30
1910 Dropped: 0 1907 Dropped: 0
1911 1908
1912 1909
1913 The latency values can also be grouped linear 1910 The latency values can also be grouped linearly by a given size with
1914 the ".buckets" modifier and specify a size (i !! 1911 the ".buckets" modifier and specify a size (in this case groups of 10).
1915 1912
1916 # echo 'hist:keys=pid,prio,lat.buckets=10:s 1913 # echo 'hist:keys=pid,prio,lat.buckets=10:sort=lat' >> \
1917 /sys/kernel/tracing/events/synthetic/ !! 1914 /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/trigger
1918 1915
1919 # event histogram 1916 # event histogram
1920 # 1917 #
1921 # trigger info: hist:keys=pid,prio,lat.buck 1918 # trigger info: hist:keys=pid,prio,lat.buckets=10:vals=hitcount:sort=lat.buckets=10:size=2048 [active]
1922 # 1919 #
1923 1920
1924 { pid: 2067, prio: 9, lat: ~ 1921 { pid: 2067, prio: 9, lat: ~ 0-9 } hitcount: 220
1925 { pid: 2068, prio: 9, lat: ~ 1922 { pid: 2068, prio: 9, lat: ~ 0-9 } hitcount: 157
1926 { pid: 2070, prio: 9, lat: ~ 1923 { pid: 2070, prio: 9, lat: ~ 0-9 } hitcount: 100
1927 { pid: 2067, prio: 120, lat: ~ 1924 { pid: 2067, prio: 120, lat: ~ 0-9 } hitcount: 6
1928 { pid: 2065, prio: 120, lat: ~ 1925 { pid: 2065, prio: 120, lat: ~ 0-9 } hitcount: 2
1929 { pid: 2066, prio: 120, lat: ~ 1926 { pid: 2066, prio: 120, lat: ~ 0-9 } hitcount: 2
1930 { pid: 2069, prio: 9, lat: ~ 1927 { pid: 2069, prio: 9, lat: ~ 0-9 } hitcount: 122
1931 { pid: 2069, prio: 120, lat: ~ 1928 { pid: 2069, prio: 120, lat: ~ 0-9 } hitcount: 8
1932 { pid: 2070, prio: 120, lat: ~ 1929 { pid: 2070, prio: 120, lat: ~ 0-9 } hitcount: 1
1933 { pid: 2068, prio: 120, lat: ~ 1930 { pid: 2068, prio: 120, lat: ~ 0-9 } hitcount: 7
1934 { pid: 2066, prio: 9, lat: ~ 1931 { pid: 2066, prio: 9, lat: ~ 0-9 } hitcount: 365
1935 { pid: 2064, prio: 120, lat: ~ 1932 { pid: 2064, prio: 120, lat: ~ 0-9 } hitcount: 35
1936 { pid: 2065, prio: 9, lat: ~ 1933 { pid: 2065, prio: 9, lat: ~ 0-9 } hitcount: 998
1937 { pid: 2071, prio: 9, lat: ~ 1934 { pid: 2071, prio: 9, lat: ~ 0-9 } hitcount: 85
1938 { pid: 2065, prio: 9, lat: ~ 1935 { pid: 2065, prio: 9, lat: ~ 10-19 } hitcount: 2
1939 { pid: 2064, prio: 120, lat: ~ 1936 { pid: 2064, prio: 120, lat: ~ 10-19 } hitcount: 2
1940 1937
1941 Totals: 1938 Totals:
1942 Hits: 2112 1939 Hits: 2112
1943 Entries: 16 1940 Entries: 16
1944 Dropped: 0 1941 Dropped: 0
1945 1942
1946 To save stacktraces, create a synthetic event <<
1947 or even just "long[]". For example, to see ho <<
1948 uninterruptible state:: <<
1949 <<
1950 # cd /sys/kernel/tracing <<
1951 # echo 's:block_lat pid_t pid; u64 delta; u <<
1952 # echo 'hist:keys=next_pid:ts=common_timest <<
1953 # echo 'hist:keys=prev_pid:delta=common_tim <<
1954 # echo 1 > events/synthetic/block_lat/enabl <<
1955 # cat trace <<
1956 <<
1957 # tracer: nop <<
1958 # <<
1959 # entries-in-buffer/entries-written: 2/2 <<
1960 # <<
1961 # _-----=> i <<
1962 # / _----=> n <<
1963 # | / _---=> h <<
1964 # || / _--=> p <<
1965 # ||| / _-=> m <<
1966 # |||| / d <<
1967 # TASK-PID CPU# ||||| TIMES <<
1968 # | | | ||||| | <<
1969 <idle>-0 [005] d..4. 521. <<
1970 => __schedule+0x448/0x7b0 <<
1971 => schedule+0x5a/0xb0 <<
1972 => io_schedule+0x42/0x70 <<
1973 => bit_wait_io+0xd/0x60 <<
1974 => __wait_on_bit+0x4b/0x140 <<
1975 => out_of_line_wait_on_bit+0x91/0xb0 <<
1976 => jbd2_journal_commit_transaction+0x1679/0 <<
1977 => kjournald2+0xa9/0x280 <<
1978 => kthread+0xe9/0x110 <<
1979 => ret_from_fork+0x2c/0x50 <<
1980 <<
1981 <...>-2 [004] d..4. 525. <<
1982 => __schedule+0x448/0x7b0 <<
1983 => schedule+0x5a/0xb0 <<
1984 => schedule_timeout+0x11a/0x150 <<
1985 => wait_for_completion_killable+0x144/0x1f0 <<
1986 => __kthread_create_on_node+0xe7/0x1e0 <<
1987 => kthread_create_on_node+0x51/0x70 <<
1988 => create_worker+0xcc/0x1a0 <<
1989 => worker_thread+0x2ad/0x380 <<
1990 => kthread+0xe9/0x110 <<
1991 => ret_from_fork+0x2c/0x50 <<
1992 <<
1993 A synthetic event that has a stacktrace field <<
1994 histogram:: <<
1995 <<
1996 # echo 'hist:keys=delta.buckets=100,stack.s <<
1997 # cat events/synthetic/block_lat/hist <<
1998 <<
1999 # event histogram <<
2000 # <<
2001 # trigger info: hist:keys=delta.buckets=100 <<
2002 # <<
2003 { delta: ~ 0-99, stack.stacktrace _ <<
2004 schedule+0x6b/0x110 <<
2005 io_schedule+0x46/0x80 <<
2006 bit_wait_io+0x11/0x80 <<
2007 __wait_on_bit+0x4e/0x120 <<
2008 out_of_line_wait_on_bit+0x8d/0xb0 <<
2009 __wait_on_buffer+0x33/0x40 <<
2010 jbd2_journal_commit_transaction+0x15 <<
2011 kjournald2+0xab/0x270 <<
2012 kthread+0xfa/0x130 <<
2013 ret_from_fork+0x29/0x50 <<
2014 } hitcount: 1 <<
2015 { delta: ~ 0-99, stack.stacktrace _ <<
2016 schedule+0x6b/0x110 <<
2017 io_schedule+0x46/0x80 <<
2018 rq_qos_wait+0xd0/0x170 <<
2019 wbt_wait+0x9e/0xf0 <<
2020 __rq_qos_throttle+0x25/0x40 <<
2021 blk_mq_submit_bio+0x2c3/0x5b0 <<
2022 __submit_bio+0xff/0x190 <<
2023 submit_bio_noacct_nocheck+0x25b/0x2b <<
2024 submit_bio_noacct+0x20b/0x600 <<
2025 submit_bio+0x28/0x90 <<
2026 ext4_bio_write_page+0x1e0/0x8c0 <<
2027 mpage_submit_page+0x60/0x80 <<
2028 mpage_process_page_bufs+0x16c/0x180 <<
2029 mpage_prepare_extent_to_map+0x23f/0x <<
2030 } hitcount: 1 <<
2031 { delta: ~ 0-99, stack.stacktrace _ <<
2032 schedule+0x6b/0x110 <<
2033 schedule_hrtimeout_range_clock+0x97/ <<
2034 schedule_hrtimeout_range+0x13/0x20 <<
2035 usleep_range_state+0x65/0x90 <<
2036 __intel_wait_for_register+0x1c1/0x23 <<
2037 intel_psr_wait_for_idle_locked+0x171 <<
2038 intel_pipe_update_start+0x169/0x360 <<
2039 intel_update_crtc+0x112/0x490 [i915] <<
2040 skl_commit_modeset_enables+0x199/0x6 <<
2041 intel_atomic_commit_tail+0x7c4/0x108 <<
2042 intel_atomic_commit_work+0x12/0x20 [ <<
2043 process_one_work+0x21c/0x3f0 <<
2044 worker_thread+0x50/0x3e0 <<
2045 kthread+0xfa/0x130 <<
2046 } hitcount: 3 <<
2047 { delta: ~ 0-99, stack.stacktrace _ <<
2048 schedule+0x6b/0x110 <<
2049 schedule_timeout+0x11e/0x160 <<
2050 __wait_for_common+0x8f/0x190 <<
2051 wait_for_completion+0x24/0x30 <<
2052 __flush_work.isra.0+0x1cc/0x360 <<
2053 flush_work+0xe/0x20 <<
2054 drm_mode_rmfb+0x18b/0x1d0 [drm] <<
2055 drm_mode_rmfb_ioctl+0x10/0x20 [drm] <<
2056 drm_ioctl_kernel+0xb8/0x150 [drm] <<
2057 drm_ioctl+0x243/0x560 [drm] <<
2058 __x64_sys_ioctl+0x92/0xd0 <<
2059 do_syscall_64+0x59/0x90 <<
2060 entry_SYSCALL_64_after_hwframe+0x72/ <<
2061 } hitcount: 1 <<
2062 { delta: ~ 0-99, stack.stacktrace _ <<
2063 schedule+0x6b/0x110 <<
2064 schedule_timeout+0x87/0x160 <<
2065 __wait_for_common+0x8f/0x190 <<
2066 wait_for_completion_timeout+0x1d/0x3 <<
2067 drm_atomic_helper_wait_for_flip_done <<
2068 intel_atomic_commit_tail+0x8ce/0x108 <<
2069 intel_atomic_commit_work+0x12/0x20 [ <<
2070 process_one_work+0x21c/0x3f0 <<
2071 worker_thread+0x50/0x3e0 <<
2072 kthread+0xfa/0x130 <<
2073 ret_from_fork+0x29/0x50 <<
2074 } hitcount: 1 <<
2075 { delta: ~ 100-199, stack.stacktrace <<
2076 schedule+0x6b/0x110 <<
2077 schedule_hrtimeout_range_clock+0x97/ <<
2078 schedule_hrtimeout_range+0x13/0x20 <<
2079 usleep_range_state+0x65/0x90 <<
2080 pci_set_low_power_state+0x17f/0x1f0 <<
2081 pci_set_power_state+0x49/0x250 <<
2082 pci_finish_runtime_suspend+0x4a/0x90 <<
2083 pci_pm_runtime_suspend+0xcb/0x1b0 <<
2084 __rpm_callback+0x48/0x120 <<
2085 rpm_callback+0x67/0x70 <<
2086 rpm_suspend+0x167/0x780 <<
2087 rpm_idle+0x25a/0x380 <<
2088 pm_runtime_work+0x93/0xc0 <<
2089 process_one_work+0x21c/0x3f0 <<
2090 } hitcount: 1 <<
2091 <<
2092 Totals: <<
2093 Hits: 10 <<
2094 Entries: 7 <<
2095 Dropped: 0 <<
2096 <<
2097 2.2.3 Hist trigger 'handlers' and 'actions' 1943 2.2.3 Hist trigger 'handlers' and 'actions'
2098 ------------------------------------------- 1944 -------------------------------------------
2099 1945
2100 A hist trigger 'action' is a function that's 1946 A hist trigger 'action' is a function that's executed (in most cases
2101 conditionally) whenever a histogram entry is 1947 conditionally) whenever a histogram entry is added or updated.
2102 1948
2103 When a histogram entry is added or updated, a 1949 When a histogram entry is added or updated, a hist trigger 'handler'
2104 is what decides whether the corresponding act 1950 is what decides whether the corresponding action is actually invoked
2105 or not. 1951 or not.
2106 1952
2107 Hist trigger handlers and actions are paired 1953 Hist trigger handlers and actions are paired together in the general
2108 form: 1954 form:
2109 1955
2110 <handler>.<action> 1956 <handler>.<action>
2111 1957
2112 To specify a handler.action pair for a given 1958 To specify a handler.action pair for a given event, simply specify
2113 that handler.action pair between colons in th 1959 that handler.action pair between colons in the hist trigger
2114 specification. 1960 specification.
2115 1961
2116 In theory, any handler can be combined with a 1962 In theory, any handler can be combined with any action, but in
2117 practice, not every handler.action combinatio 1963 practice, not every handler.action combination is currently supported;
2118 if a given handler.action combination isn't s 1964 if a given handler.action combination isn't supported, the hist
2119 trigger will fail with -EINVAL; 1965 trigger will fail with -EINVAL;
2120 1966
2121 The default 'handler.action' if none is expli 1967 The default 'handler.action' if none is explicitly specified is as it
2122 always has been, to simply update the set of 1968 always has been, to simply update the set of values associated with an
2123 entry. Some applications, however, may want 1969 entry. Some applications, however, may want to perform additional
2124 actions at that point, such as generate anoth 1970 actions at that point, such as generate another event, or compare and
2125 save a maximum. 1971 save a maximum.
2126 1972
2127 The supported handlers and actions are listed 1973 The supported handlers and actions are listed below, and each is
2128 described in more detail in the following par 1974 described in more detail in the following paragraphs, in the context
2129 of descriptions of some common and useful han 1975 of descriptions of some common and useful handler.action combinations.
2130 1976
2131 The available handlers are: 1977 The available handlers are:
2132 1978
2133 - onmatch(matching.event) - invoke actio 1979 - onmatch(matching.event) - invoke action on any addition or update
2134 - onmax(var) - invoke actio 1980 - onmax(var) - invoke action if var exceeds current max
2135 - onchange(var) - invoke actio 1981 - onchange(var) - invoke action if var changes
2136 1982
2137 The available actions are: 1983 The available actions are:
2138 1984
2139 - trace(<synthetic_event_name>,param list) 1985 - trace(<synthetic_event_name>,param list) - generate synthetic event
2140 - save(field,...) 1986 - save(field,...) - save current event fields
2141 - snapshot() 1987 - snapshot() - snapshot the trace buffer
2142 1988
2143 The following commonly-used handler.action pa 1989 The following commonly-used handler.action pairs are available:
2144 1990
2145 - onmatch(matching.event).trace(<synthetic_ 1991 - onmatch(matching.event).trace(<synthetic_event_name>,param list)
2146 1992
2147 The 'onmatch(matching.event).trace(<synth 1993 The 'onmatch(matching.event).trace(<synthetic_event_name>,param
2148 list)' hist trigger action is invoked whe 1994 list)' hist trigger action is invoked whenever an event matches
2149 and the histogram entry would be added or 1995 and the histogram entry would be added or updated. It causes the
2150 named synthetic event to be generated wit 1996 named synthetic event to be generated with the values given in the
2151 'param list'. The result is the generati 1997 'param list'. The result is the generation of a synthetic event
2152 that consists of the values contained in 1998 that consists of the values contained in those variables at the
2153 time the invoking event was hit. For exa 1999 time the invoking event was hit. For example, if the synthetic
2154 event name is 'wakeup_latency', a wakeup_ 2000 event name is 'wakeup_latency', a wakeup_latency event is
2155 generated using onmatch(event).trace(wake 2001 generated using onmatch(event).trace(wakeup_latency,arg1,arg2).
2156 2002
2157 There is also an equivalent alternative f 2003 There is also an equivalent alternative form available for
2158 generating synthetic events. In this for 2004 generating synthetic events. In this form, the synthetic event
2159 name is used as if it were a function nam 2005 name is used as if it were a function name. For example, using
2160 the 'wakeup_latency' synthetic event name 2006 the 'wakeup_latency' synthetic event name again, the
2161 wakeup_latency event would be generated b 2007 wakeup_latency event would be generated by invoking it as if it
2162 were a function call, with the event fiel 2008 were a function call, with the event field values passed in as
2163 arguments: onmatch(event).wakeup_latency( 2009 arguments: onmatch(event).wakeup_latency(arg1,arg2). The syntax
2164 for this form is: 2010 for this form is:
2165 2011
2166 onmatch(matching.event).<synthetic_even 2012 onmatch(matching.event).<synthetic_event_name>(param list)
2167 2013
2168 In either case, the 'param list' consists 2014 In either case, the 'param list' consists of one or more
2169 parameters which may be either variables 2015 parameters which may be either variables or fields defined on
2170 either the 'matching.event' or the target 2016 either the 'matching.event' or the target event. The variables or
2171 fields specified in the param list may be 2017 fields specified in the param list may be either fully-qualified
2172 or unqualified. If a variable is specifi 2018 or unqualified. If a variable is specified as unqualified, it
2173 must be unique between the two events. A 2019 must be unique between the two events. A field name used as a
2174 param can be unqualified if it refers to 2020 param can be unqualified if it refers to the target event, but
2175 must be fully qualified if it refers to t 2021 must be fully qualified if it refers to the matching event. A
2176 fully-qualified name is of the form 'syst 2022 fully-qualified name is of the form 'system.event_name.$var_name'
2177 or 'system.event_name.field'. 2023 or 'system.event_name.field'.
2178 2024
2179 The 'matching.event' specification is sim 2025 The 'matching.event' specification is simply the fully qualified
2180 event name of the event that matches the 2026 event name of the event that matches the target event for the
2181 onmatch() functionality, in the form 'sys 2027 onmatch() functionality, in the form 'system.event_name'. Histogram
2182 keys of both events are compared to find 2028 keys of both events are compared to find if events match. In case
2183 multiple histogram keys are used, they al 2029 multiple histogram keys are used, they all must match in the specified
2184 order. 2030 order.
2185 2031
2186 Finally, the number and type of variables 2032 Finally, the number and type of variables/fields in the 'param
2187 list' must match the number and types of 2033 list' must match the number and types of the fields in the
2188 synthetic event being generated. 2034 synthetic event being generated.
2189 2035
2190 As an example the below defines a simple 2036 As an example the below defines a simple synthetic event and uses
2191 a variable defined on the sched_wakeup_ne 2037 a variable defined on the sched_wakeup_new event as a parameter
2192 when invoking the synthetic event. Here 2038 when invoking the synthetic event. Here we define the synthetic
2193 event:: 2039 event::
2194 2040
2195 # echo 'wakeup_new_test pid_t pid' >> \ 2041 # echo 'wakeup_new_test pid_t pid' >> \
2196 /sys/kernel/tracing/synthetic_ev !! 2042 /sys/kernel/debug/tracing/synthetic_events
2197 2043
2198 # cat /sys/kernel/tracing/synthetic_eve !! 2044 # cat /sys/kernel/debug/tracing/synthetic_events
2199 wakeup_new_test pid_t pid 2045 wakeup_new_test pid_t pid
2200 2046
2201 The following hist trigger both defines t 2047 The following hist trigger both defines the missing testpid
2202 variable and specifies an onmatch() actio 2048 variable and specifies an onmatch() action that generates a
2203 wakeup_new_test synthetic event whenever 2049 wakeup_new_test synthetic event whenever a sched_wakeup_new event
2204 occurs, which because of the 'if comm == 2050 occurs, which because of the 'if comm == "cyclictest"' filter only
2205 happens when the executable is cyclictest 2051 happens when the executable is cyclictest::
2206 2052
2207 # echo 'hist:keys=$testpid:testpid=pid: 2053 # echo 'hist:keys=$testpid:testpid=pid:onmatch(sched.sched_wakeup_new).\
2208 wakeup_new_test($testpid) if co 2054 wakeup_new_test($testpid) if comm=="cyclictest"' >> \
2209 /sys/kernel/tracing/events/sche !! 2055 /sys/kernel/debug/tracing/events/sched/sched_wakeup_new/trigger
2210 2056
2211 Or, equivalently, using the 'trace' keywo !! 2057 Or, equivalently, using the 'trace' keyword syntax:
2212 2058
2213 # echo 'hist:keys=$testpid:testpid=pid: !! 2059 # echo 'hist:keys=$testpid:testpid=pid:onmatch(sched.sched_wakeup_new).\
2214 trace(wakeup_new_test,$testpid) !! 2060 trace(wakeup_new_test,$testpid) if comm=="cyclictest"' >> \
2215 /sys/kernel/tracing/events/sche !! 2061 /sys/kernel/debug/tracing/events/sched/sched_wakeup_new/trigger
2216 2062
2217 Creating and displaying a histogram based 2063 Creating and displaying a histogram based on those events is now
2218 just a matter of using the fields and new 2064 just a matter of using the fields and new synthetic event in the
2219 tracing/events/synthetic directory, as us 2065 tracing/events/synthetic directory, as usual::
2220 2066
2221 # echo 'hist:keys=pid:sort=pid' >> \ 2067 # echo 'hist:keys=pid:sort=pid' >> \
2222 /sys/kernel/tracing/events/synth !! 2068 /sys/kernel/debug/tracing/events/synthetic/wakeup_new_test/trigger
2223 2069
2224 Running 'cyclictest' should cause wakeup_ 2070 Running 'cyclictest' should cause wakeup_new events to generate
2225 wakeup_new_test synthetic events which sh 2071 wakeup_new_test synthetic events which should result in histogram
2226 output in the wakeup_new_test event's his 2072 output in the wakeup_new_test event's hist file::
2227 2073
2228 # cat /sys/kernel/tracing/events/synthe !! 2074 # cat /sys/kernel/debug/tracing/events/synthetic/wakeup_new_test/hist
2229 2075
2230 A more typical usage would be to use two 2076 A more typical usage would be to use two events to calculate a
2231 latency. The following example uses a se 2077 latency. The following example uses a set of hist triggers to
2232 produce a 'wakeup_latency' histogram. 2078 produce a 'wakeup_latency' histogram.
2233 2079
2234 First, we define a 'wakeup_latency' synth 2080 First, we define a 'wakeup_latency' synthetic event::
2235 2081
2236 # echo 'wakeup_latency u64 lat; pid_t p 2082 # echo 'wakeup_latency u64 lat; pid_t pid; int prio' >> \
2237 /sys/kernel/tracing/synthetic_e !! 2083 /sys/kernel/debug/tracing/synthetic_events
2238 2084
2239 Next, we specify that whenever we see a s 2085 Next, we specify that whenever we see a sched_waking event for a
2240 cyclictest thread, save the timestamp in 2086 cyclictest thread, save the timestamp in a 'ts0' variable::
2241 2087
2242 # echo 'hist:keys=$saved_pid:saved_pid= 2088 # echo 'hist:keys=$saved_pid:saved_pid=pid:ts0=common_timestamp.usecs \
2243 if comm=="cyclictest"' >> \ 2089 if comm=="cyclictest"' >> \
2244 /sys/kernel/tracing/events/sche !! 2090 /sys/kernel/debug/tracing/events/sched/sched_waking/trigger
2245 2091
2246 Then, when the corresponding thread is ac 2092 Then, when the corresponding thread is actually scheduled onto the
2247 CPU by a sched_switch event (saved_pid ma 2093 CPU by a sched_switch event (saved_pid matches next_pid), calculate
2248 the latency and use that along with anoth 2094 the latency and use that along with another variable and an event field
2249 to generate a wakeup_latency synthetic ev 2095 to generate a wakeup_latency synthetic event::
2250 2096
2251 # echo 'hist:keys=next_pid:wakeup_lat=c 2097 # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:\
2252 onmatch(sched.sched_waking).wak 2098 onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,\
2253 $saved_pid,next_prio) i 2099 $saved_pid,next_prio) if next_comm=="cyclictest"' >> \
2254 /sys/kernel/tracing/events/sche !! 2100 /sys/kernel/debug/tracing/events/sched/sched_switch/trigger
2255 2101
2256 We also need to create a histogram on the 2102 We also need to create a histogram on the wakeup_latency synthetic
2257 event in order to aggregate the generated 2103 event in order to aggregate the generated synthetic event data::
2258 2104
2259 # echo 'hist:keys=pid,prio,lat:sort=pid 2105 # echo 'hist:keys=pid,prio,lat:sort=pid,lat' >> \
2260 /sys/kernel/tracing/events/synt !! 2106 /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/trigger
2261 2107
2262 Finally, once we've run cyclictest to act 2108 Finally, once we've run cyclictest to actually generate some
2263 events, we can see the output by looking 2109 events, we can see the output by looking at the wakeup_latency
2264 synthetic event's hist file:: 2110 synthetic event's hist file::
2265 2111
2266 # cat /sys/kernel/tracing/events/synthe !! 2112 # cat /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/hist
2267 2113
2268 - onmax(var).save(field,.. .) 2114 - onmax(var).save(field,.. .)
2269 2115
2270 The 'onmax(var).save(field,...)' hist tri 2116 The 'onmax(var).save(field,...)' hist trigger action is invoked
2271 whenever the value of 'var' associated wi 2117 whenever the value of 'var' associated with a histogram entry
2272 exceeds the current maximum contained in 2118 exceeds the current maximum contained in that variable.
2273 2119
2274 The end result is that the trace event fi 2120 The end result is that the trace event fields specified as the
2275 onmax.save() params will be saved if 'var 2121 onmax.save() params will be saved if 'var' exceeds the current
2276 maximum for that hist trigger entry. Thi 2122 maximum for that hist trigger entry. This allows context from the
2277 event that exhibited the new maximum to b 2123 event that exhibited the new maximum to be saved for later
2278 reference. When the histogram is display 2124 reference. When the histogram is displayed, additional fields
2279 displaying the saved values will be print 2125 displaying the saved values will be printed.
2280 2126
2281 As an example the below defines a couple 2127 As an example the below defines a couple of hist triggers, one for
2282 sched_waking and another for sched_switch 2128 sched_waking and another for sched_switch, keyed on pid. Whenever
2283 a sched_waking occurs, the timestamp is s 2129 a sched_waking occurs, the timestamp is saved in the entry
2284 corresponding to the current pid, and whe 2130 corresponding to the current pid, and when the scheduler switches
2285 back to that pid, the timestamp differenc 2131 back to that pid, the timestamp difference is calculated. If the
2286 resulting latency, stored in wakeup_lat, 2132 resulting latency, stored in wakeup_lat, exceeds the current
2287 maximum latency, the values specified in 2133 maximum latency, the values specified in the save() fields are
2288 recorded:: 2134 recorded::
2289 2135
2290 # echo 'hist:keys=pid:ts0=common_timest 2136 # echo 'hist:keys=pid:ts0=common_timestamp.usecs \
2291 if comm=="cyclictest"' >> \ 2137 if comm=="cyclictest"' >> \
2292 /sys/kernel/tracing/events/sche !! 2138 /sys/kernel/debug/tracing/events/sched/sched_waking/trigger
2293 2139
2294 # echo 'hist:keys=next_pid:\ 2140 # echo 'hist:keys=next_pid:\
2295 wakeup_lat=common_timestamp.use 2141 wakeup_lat=common_timestamp.usecs-$ts0:\
2296 onmax($wakeup_lat).save(next_co 2142 onmax($wakeup_lat).save(next_comm,prev_pid,prev_prio,prev_comm) \
2297 if next_comm=="cyclictest"' >> 2143 if next_comm=="cyclictest"' >> \
2298 /sys/kernel/tracing/events/sche !! 2144 /sys/kernel/debug/tracing/events/sched/sched_switch/trigger
2299 2145
2300 When the histogram is displayed, the max 2146 When the histogram is displayed, the max value and the saved
2301 values corresponding to the max are displ 2147 values corresponding to the max are displayed following the rest
2302 of the fields:: 2148 of the fields::
2303 2149
2304 # cat /sys/kernel/tracing/events/sched/ !! 2150 # cat /sys/kernel/debug/tracing/events/sched/sched_switch/hist
2305 { next_pid: 2255 } hitcount: 2151 { next_pid: 2255 } hitcount: 239
2306 common_timestamp-ts0: 0 2152 common_timestamp-ts0: 0
2307 max: 27 2153 max: 27
2308 next_comm: cyclictest 2154 next_comm: cyclictest
2309 prev_pid: 0 prev_prio: 2155 prev_pid: 0 prev_prio: 120 prev_comm: swapper/1
2310 2156
2311 { next_pid: 2256 } hitcount: 2157 { next_pid: 2256 } hitcount: 2355
2312 common_timestamp-ts0: 0 2158 common_timestamp-ts0: 0
2313 max: 49 next_comm: cyclict 2159 max: 49 next_comm: cyclictest
2314 prev_pid: 0 prev_prio: 2160 prev_pid: 0 prev_prio: 120 prev_comm: swapper/0
2315 2161
2316 Totals: 2162 Totals:
2317 Hits: 12970 2163 Hits: 12970
2318 Entries: 2 2164 Entries: 2
2319 Dropped: 0 2165 Dropped: 0
2320 2166
2321 - onmax(var).snapshot() 2167 - onmax(var).snapshot()
2322 2168
2323 The 'onmax(var).snapshot()' hist trigger 2169 The 'onmax(var).snapshot()' hist trigger action is invoked
2324 whenever the value of 'var' associated wi 2170 whenever the value of 'var' associated with a histogram entry
2325 exceeds the current maximum contained in 2171 exceeds the current maximum contained in that variable.
2326 2172
2327 The end result is that a global snapshot 2173 The end result is that a global snapshot of the trace buffer will
2328 be saved in the tracing/snapshot file if 2174 be saved in the tracing/snapshot file if 'var' exceeds the current
2329 maximum for any hist trigger entry. 2175 maximum for any hist trigger entry.
2330 2176
2331 Note that in this case the maximum is a g 2177 Note that in this case the maximum is a global maximum for the
2332 current trace instance, which is the maxi 2178 current trace instance, which is the maximum across all buckets of
2333 the histogram. The key of the specific t 2179 the histogram. The key of the specific trace event that caused
2334 the global maximum and the global maximum 2180 the global maximum and the global maximum itself are displayed,
2335 along with a message stating that a snaps 2181 along with a message stating that a snapshot has been taken and
2336 where to find it. The user can use the k 2182 where to find it. The user can use the key information displayed
2337 to locate the corresponding bucket in the 2183 to locate the corresponding bucket in the histogram for even more
2338 detail. 2184 detail.
2339 2185
2340 As an example the below defines a couple 2186 As an example the below defines a couple of hist triggers, one for
2341 sched_waking and another for sched_switch 2187 sched_waking and another for sched_switch, keyed on pid. Whenever
2342 a sched_waking event occurs, the timestam 2188 a sched_waking event occurs, the timestamp is saved in the entry
2343 corresponding to the current pid, and whe 2189 corresponding to the current pid, and when the scheduler switches
2344 back to that pid, the timestamp differenc 2190 back to that pid, the timestamp difference is calculated. If the
2345 resulting latency, stored in wakeup_lat, 2191 resulting latency, stored in wakeup_lat, exceeds the current
2346 maximum latency, a snapshot is taken. As 2192 maximum latency, a snapshot is taken. As part of the setup, all
2347 the scheduler events are also enabled, wh 2193 the scheduler events are also enabled, which are the events that
2348 will show up in the snapshot when it is t !! 2194 will show up in the snapshot when it is taken at some point:
2349 <<
2350 # echo 1 > /sys/kernel/tracing/events/s <<
2351 2195
2352 # echo 'hist:keys=pid:ts0=common_timest !! 2196 # echo 1 > /sys/kernel/debug/tracing/events/sched/enable
2353 if comm=="cyclictest"' >> \ <<
2354 /sys/kernel/tracing/events/sche <<
2355 2197
2356 # echo 'hist:keys=next_pid:wakeup_lat=c !! 2198 # echo 'hist:keys=pid:ts0=common_timestamp.usecs \
2357 onmax($wakeup_lat).save(next_pr !! 2199 if comm=="cyclictest"' >> \
2358 prev_comm):onmax($wakeup_lat).s !! 2200 /sys/kernel/debug/tracing/events/sched/sched_waking/trigger
2359 if next_comm=="cyclictest"' >> !! 2201
2360 /sys/kernel/tracing/events/sche !! 2202 # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0: \
>> 2203 onmax($wakeup_lat).save(next_prio,next_comm,prev_pid,prev_prio, \
>> 2204 prev_comm):onmax($wakeup_lat).snapshot() \
>> 2205 if next_comm=="cyclictest"' >> \
>> 2206 /sys/kernel/debug/tracing/events/sched/sched_switch/trigger
2361 2207
2362 When the histogram is displayed, for each 2208 When the histogram is displayed, for each bucket the max value
2363 and the saved values corresponding to the 2209 and the saved values corresponding to the max are displayed
2364 following the rest of the fields. 2210 following the rest of the fields.
2365 2211
2366 If a snapshot was taken, there is also a 2212 If a snapshot was taken, there is also a message indicating that,
2367 along with the value and event that trigg !! 2213 along with the value and event that triggered the global maximum:
2368 2214
2369 # cat /sys/kernel/tracing/events/sched/ !! 2215 # cat /sys/kernel/debug/tracing/events/sched/sched_switch/hist
2370 { next_pid: 2101 } hitcount: !! 2216 { next_pid: 2101 } hitcount: 200
2371 max: 52 next_prio: !! 2217 max: 52 next_prio: 120 next_comm: cyclictest \
2372 prev_pid: 0 prev_prio: !! 2218 prev_pid: 0 prev_prio: 120 prev_comm: swapper/6
2373 2219
2374 { next_pid: 2103 } hitcount: !! 2220 { next_pid: 2103 } hitcount: 1326
2375 max: 572 next_prio: !! 2221 max: 572 next_prio: 19 next_comm: cyclictest \
2376 prev_pid: 0 prev_prio: !! 2222 prev_pid: 0 prev_prio: 120 prev_comm: swapper/1
2377 2223
2378 { next_pid: 2102 } hitcount: !! 2224 { next_pid: 2102 } hitcount: 1982 \
2379 max: 74 next_prio: !! 2225 max: 74 next_prio: 19 next_comm: cyclictest \
2380 prev_pid: 0 prev_prio: !! 2226 prev_pid: 0 prev_prio: 120 prev_comm: swapper/5
2381 <<
2382 Snapshot taken (see tracing/snapshot). <<
2383 triggering value { onmax($wakeup_la <<
2384 triggered by event with key: { next <<
2385 2227
2386 Totals: !! 2228 Snapshot taken (see tracing/snapshot). Details:
2387 Hits: 3508 !! 2229 triggering value { onmax($wakeup_lat) }: 572 \
2388 Entries: 3 !! 2230 triggered by event with key: { next_pid: 2103 }
2389 Dropped: 0 !! 2231
>> 2232 Totals:
>> 2233 Hits: 3508
>> 2234 Entries: 3
>> 2235 Dropped: 0
2390 2236
2391 In the above case, the event that trigger 2237 In the above case, the event that triggered the global maximum has
2392 the key with next_pid == 2103. If you lo 2238 the key with next_pid == 2103. If you look at the bucket that has
2393 2103 as the key, you'll find the addition 2239 2103 as the key, you'll find the additional values save()'d along
2394 with the local maximum for that bucket, w 2240 with the local maximum for that bucket, which should be the same
2395 as the global maximum (since that was the 2241 as the global maximum (since that was the same value that
2396 triggered the global snapshot). 2242 triggered the global snapshot).
2397 2243
2398 And finally, looking at the snapshot data 2244 And finally, looking at the snapshot data should show at or near
2399 the end the event that triggered the snap 2245 the end the event that triggered the snapshot (in this case you
2400 can verify the timestamps between the sch 2246 can verify the timestamps between the sched_waking and
2401 sched_switch events, which should match t 2247 sched_switch events, which should match the time displayed in the
2402 global maximum):: 2248 global maximum)::
2403 2249
2404 # cat /sys/kernel/tracing/snapshot !! 2250 # cat /sys/kernel/debug/tracing/snapshot
2405 2251
2406 <...>-2103 [005] d..3 309.873125: 2252 <...>-2103 [005] d..3 309.873125: sched_switch: prev_comm=cyclictest prev_pid=2103 prev_prio=19 prev_state=D ==> next_comm=swapper/5 next_pid=0 next_prio=120
2407 <idle>-0 [005] d.h3 309.873611 2253 <idle>-0 [005] d.h3 309.873611: sched_waking: comm=cyclictest pid=2102 prio=19 target_cpu=005
2408 <idle>-0 [005] dNh4 309.873613 2254 <idle>-0 [005] dNh4 309.873613: sched_wakeup: comm=cyclictest pid=2102 prio=19 target_cpu=005
2409 <idle>-0 [005] d..3 309.873616 2255 <idle>-0 [005] d..3 309.873616: sched_switch: prev_comm=swapper/5 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=cyclictest next_pid=2102 next_prio=19
2410 <...>-2102 [005] d..3 309.873625: 2256 <...>-2102 [005] d..3 309.873625: sched_switch: prev_comm=cyclictest prev_pid=2102 prev_prio=19 prev_state=D ==> next_comm=swapper/5 next_pid=0 next_prio=120
2411 <idle>-0 [005] d.h3 309.874624 2257 <idle>-0 [005] d.h3 309.874624: sched_waking: comm=cyclictest pid=2102 prio=19 target_cpu=005
2412 <idle>-0 [005] dNh4 309.874626 2258 <idle>-0 [005] dNh4 309.874626: sched_wakeup: comm=cyclictest pid=2102 prio=19 target_cpu=005
2413 <idle>-0 [005] dNh3 309.874628 2259 <idle>-0 [005] dNh3 309.874628: sched_waking: comm=cyclictest pid=2103 prio=19 target_cpu=005
2414 <idle>-0 [005] dNh4 309.874630 2260 <idle>-0 [005] dNh4 309.874630: sched_wakeup: comm=cyclictest pid=2103 prio=19 target_cpu=005
2415 <idle>-0 [005] d..3 309.874633 2261 <idle>-0 [005] d..3 309.874633: sched_switch: prev_comm=swapper/5 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=cyclictest next_pid=2102 next_prio=19
2416 <idle>-0 [004] d.h3 309.874757 2262 <idle>-0 [004] d.h3 309.874757: sched_waking: comm=gnome-terminal- pid=1699 prio=120 target_cpu=004
2417 <idle>-0 [004] dNh4 309.874762 2263 <idle>-0 [004] dNh4 309.874762: sched_wakeup: comm=gnome-terminal- pid=1699 prio=120 target_cpu=004
2418 <idle>-0 [004] d..3 309.874766 2264 <idle>-0 [004] d..3 309.874766: sched_switch: prev_comm=swapper/4 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=gnome-terminal- next_pid=1699 next_prio=120
2419 gnome-terminal--1699 [004] d.h2 309.8 2265 gnome-terminal--1699 [004] d.h2 309.874941: sched_stat_runtime: comm=gnome-terminal- pid=1699 runtime=180706 [ns] vruntime=1126870572 [ns]
2420 <idle>-0 [003] d.s4 309.874956 2266 <idle>-0 [003] d.s4 309.874956: sched_waking: comm=rcu_sched pid=9 prio=120 target_cpu=007
2421 <idle>-0 [003] d.s5 309.874960 2267 <idle>-0 [003] d.s5 309.874960: sched_wake_idle_without_ipi: cpu=7
2422 <idle>-0 [003] d.s5 309.874961 2268 <idle>-0 [003] d.s5 309.874961: sched_wakeup: comm=rcu_sched pid=9 prio=120 target_cpu=007
2423 <idle>-0 [007] d..3 309.874963 2269 <idle>-0 [007] d..3 309.874963: sched_switch: prev_comm=swapper/7 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=rcu_sched next_pid=9 next_prio=120
2424 rcu_sched-9 [007] d..3 309.874973 2270 rcu_sched-9 [007] d..3 309.874973: sched_stat_runtime: comm=rcu_sched pid=9 runtime=13646 [ns] vruntime=22531430286 [ns]
2425 rcu_sched-9 [007] d..3 309.874978 2271 rcu_sched-9 [007] d..3 309.874978: sched_switch: prev_comm=rcu_sched prev_pid=9 prev_prio=120 prev_state=R+ ==> next_comm=swapper/7 next_pid=0 next_prio=120
2426 <...>-2102 [005] d..4 309.874994 2272 <...>-2102 [005] d..4 309.874994: sched_migrate_task: comm=cyclictest pid=2103 prio=19 orig_cpu=5 dest_cpu=1
2427 <...>-2102 [005] d..4 309.875185 2273 <...>-2102 [005] d..4 309.875185: sched_wake_idle_without_ipi: cpu=1
2428 <idle>-0 [001] d..3 309.875200 2274 <idle>-0 [001] d..3 309.875200: sched_switch: prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=S ==> next_comm=cyclictest next_pid=2103 next_prio=19
2429 2275
2430 - onchange(var).save(field,.. .) 2276 - onchange(var).save(field,.. .)
2431 2277
2432 The 'onchange(var).save(field,...)' hist 2278 The 'onchange(var).save(field,...)' hist trigger action is invoked
2433 whenever the value of 'var' associated wi 2279 whenever the value of 'var' associated with a histogram entry
2434 changes. 2280 changes.
2435 2281
2436 The end result is that the trace event fi 2282 The end result is that the trace event fields specified as the
2437 onchange.save() params will be saved if ' 2283 onchange.save() params will be saved if 'var' changes for that
2438 hist trigger entry. This allows context 2284 hist trigger entry. This allows context from the event that
2439 changed the value to be saved for later r 2285 changed the value to be saved for later reference. When the
2440 histogram is displayed, additional fields 2286 histogram is displayed, additional fields displaying the saved
2441 values will be printed. 2287 values will be printed.
2442 2288
2443 - onchange(var).snapshot() 2289 - onchange(var).snapshot()
2444 2290
2445 The 'onchange(var).snapshot()' hist trigg 2291 The 'onchange(var).snapshot()' hist trigger action is invoked
2446 whenever the value of 'var' associated wi 2292 whenever the value of 'var' associated with a histogram entry
2447 changes. 2293 changes.
2448 2294
2449 The end result is that a global snapshot 2295 The end result is that a global snapshot of the trace buffer will
2450 be saved in the tracing/snapshot file if 2296 be saved in the tracing/snapshot file if 'var' changes for any
2451 hist trigger entry. 2297 hist trigger entry.
2452 2298
2453 Note that in this case the changed value 2299 Note that in this case the changed value is a global variable
2454 associated with current trace instance. 2300 associated with current trace instance. The key of the specific
2455 trace event that caused the value to chan 2301 trace event that caused the value to change and the global value
2456 itself are displayed, along with a messag 2302 itself are displayed, along with a message stating that a snapshot
2457 has been taken and where to find it. The 2303 has been taken and where to find it. The user can use the key
2458 information displayed to locate the corre 2304 information displayed to locate the corresponding bucket in the
2459 histogram for even more detail. 2305 histogram for even more detail.
2460 2306
2461 As an example the below defines a hist tr 2307 As an example the below defines a hist trigger on the tcp_probe
2462 event, keyed on dport. Whenever a tcp_pr 2308 event, keyed on dport. Whenever a tcp_probe event occurs, the
2463 cwnd field is checked against the current 2309 cwnd field is checked against the current value stored in the
2464 $cwnd variable. If the value has changed 2310 $cwnd variable. If the value has changed, a snapshot is taken.
2465 As part of the setup, all the scheduler a 2311 As part of the setup, all the scheduler and tcp events are also
2466 enabled, which are the events that will s 2312 enabled, which are the events that will show up in the snapshot
2467 when it is taken at some point:: !! 2313 when it is taken at some point:
2468 2314
2469 # echo 1 > /sys/kernel/tracing/events/s !! 2315 # echo 1 > /sys/kernel/debug/tracing/events/sched/enable
2470 # echo 1 > /sys/kernel/tracing/events/t !! 2316 # echo 1 > /sys/kernel/debug/tracing/events/tcp/enable
2471 2317
2472 # echo 'hist:keys=dport:cwnd=snd_cwnd: !! 2318 # echo 'hist:keys=dport:cwnd=snd_cwnd: \
2473 onchange($cwnd).save(snd_wnd,sr !! 2319 onchange($cwnd).save(snd_wnd,srtt,rcv_wnd): \
2474 onchange($cwnd).snapshot()' >> !! 2320 onchange($cwnd).snapshot()' >> \
2475 /sys/kernel/tracing/events/tcp/ !! 2321 /sys/kernel/debug/tracing/events/tcp/tcp_probe/trigger
2476 2322
2477 When the histogram is displayed, for each 2323 When the histogram is displayed, for each bucket the tracked value
2478 and the saved values corresponding to tha 2324 and the saved values corresponding to that value are displayed
2479 following the rest of the fields. 2325 following the rest of the fields.
2480 2326
2481 If a snapshot was taken, there is also a 2327 If a snapshot was taken, there is also a message indicating that,
2482 along with the value and event that trigg 2328 along with the value and event that triggered the snapshot::
2483 2329
2484 # cat /sys/kernel/tracing/events/tcp/tc !! 2330 # cat /sys/kernel/debug/tracing/events/tcp/tcp_probe/hist
2485 2331
2486 { dport: 1521 } hitcount: 2332 { dport: 1521 } hitcount: 8
2487 changed: 10 snd_wnd: 35 2333 changed: 10 snd_wnd: 35456 srtt: 154262 rcv_wnd: 42112
2488 2334
2489 { dport: 80 } hitcount: 2335 { dport: 80 } hitcount: 23
2490 changed: 10 snd_wnd: 28 2336 changed: 10 snd_wnd: 28960 srtt: 19604 rcv_wnd: 29312
2491 2337
2492 { dport: 9001 } hitcount: 2338 { dport: 9001 } hitcount: 172
2493 changed: 10 snd_wnd: 48 2339 changed: 10 snd_wnd: 48384 srtt: 260444 rcv_wnd: 55168
2494 2340
2495 { dport: 443 } hitcount: 2341 { dport: 443 } hitcount: 211
2496 changed: 10 snd_wnd: 26 2342 changed: 10 snd_wnd: 26960 srtt: 17379 rcv_wnd: 28800
2497 2343
2498 Snapshot taken (see tracing/snapshot). !! 2344 Snapshot taken (see tracing/snapshot). Details::
2499 2345
2500 triggering value { onchange($cwnd) !! 2346 triggering value { onchange($cwnd) }: 10
2501 triggered by event with key: { dpor !! 2347 triggered by event with key: { dport: 80 }
2502 2348
2503 Totals: 2349 Totals:
2504 Hits: 414 2350 Hits: 414
2505 Entries: 4 2351 Entries: 4
2506 Dropped: 0 2352 Dropped: 0
2507 2353
2508 In the above case, the event that trigger 2354 In the above case, the event that triggered the snapshot has the
2509 key with dport == 80. If you look at the 2355 key with dport == 80. If you look at the bucket that has 80 as
2510 the key, you'll find the additional value 2356 the key, you'll find the additional values save()'d along with the
2511 changed value for that bucket, which shou 2357 changed value for that bucket, which should be the same as the
2512 global changed value (since that was the 2358 global changed value (since that was the same value that triggered
2513 the global snapshot). 2359 the global snapshot).
2514 2360
2515 And finally, looking at the snapshot data 2361 And finally, looking at the snapshot data should show at or near
2516 the end the event that triggered the snap 2362 the end the event that triggered the snapshot::
2517 2363
2518 # cat /sys/kernel/tracing/snapshot !! 2364 # cat /sys/kernel/debug/tracing/snapshot
2519 2365
2520 gnome-shell-1261 [006] dN.3 49.8 2366 gnome-shell-1261 [006] dN.3 49.823113: sched_stat_runtime: comm=gnome-shell pid=1261 runtime=49347 [ns] vruntime=1835730389 [ns]
2521 kworker/u16:4-773 [003] d..3 49.8 2367 kworker/u16:4-773 [003] d..3 49.823114: sched_switch: prev_comm=kworker/u16:4 prev_pid=773 prev_prio=120 prev_state=R+ ==> next_comm=kworker/3:2 next_pid=135 next_prio=120
2522 gnome-shell-1261 [006] d..3 49.8 2368 gnome-shell-1261 [006] d..3 49.823114: sched_switch: prev_comm=gnome-shell prev_pid=1261 prev_prio=120 prev_state=R+ ==> next_comm=kworker/6:2 next_pid=387 next_prio=120
2523 kworker/3:2-135 [003] d..3 49.8 2369 kworker/3:2-135 [003] d..3 49.823118: sched_stat_runtime: comm=kworker/3:2 pid=135 runtime=5339 [ns] vruntime=17815800388 [ns]
2524 kworker/6:2-387 [006] d..3 49.8 2370 kworker/6:2-387 [006] d..3 49.823120: sched_stat_runtime: comm=kworker/6:2 pid=387 runtime=9594 [ns] vruntime=14589605367 [ns]
2525 kworker/6:2-387 [006] d..3 49.8 2371 kworker/6:2-387 [006] d..3 49.823122: sched_switch: prev_comm=kworker/6:2 prev_pid=387 prev_prio=120 prev_state=R+ ==> next_comm=gnome-shell next_pid=1261 next_prio=120
2526 kworker/3:2-135 [003] d..3 49.8 2372 kworker/3:2-135 [003] d..3 49.823123: sched_switch: prev_comm=kworker/3:2 prev_pid=135 prev_prio=120 prev_state=T ==> next_comm=swapper/3 next_pid=0 next_prio=120
2527 <idle>-0 [004] ..s7 49.8 2373 <idle>-0 [004] ..s7 49.823798: tcp_probe: src=10.0.0.10:54326 dest=23.215.104.193:80 mark=0x0 length=32 snd_nxt=0xe3ae2ff5 snd_una=0xe3ae2ecd snd_cwnd=10 ssthresh=2147483647 snd_wnd=28960 srtt=19604 rcv_wnd=29312
2528 2374
2529 3. User space creating a trigger 2375 3. User space creating a trigger
2530 -------------------------------- 2376 --------------------------------
2531 2377
2532 Writing into /sys/kernel/tracing/trace_marker 2378 Writing into /sys/kernel/tracing/trace_marker writes into the ftrace
2533 ring buffer. This can also act like an event, 2379 ring buffer. This can also act like an event, by writing into the trigger
2534 file located in /sys/kernel/tracing/events/ft 2380 file located in /sys/kernel/tracing/events/ftrace/print/
2535 2381
2536 Modifying cyclictest to write into the trace_ 2382 Modifying cyclictest to write into the trace_marker file before it sleeps
2537 and after it wakes up, something like this:: 2383 and after it wakes up, something like this::
2538 2384
2539 static void traceputs(char *str) 2385 static void traceputs(char *str)
2540 { 2386 {
2541 /* tracemark_fd is the trace_marker f 2387 /* tracemark_fd is the trace_marker file descriptor */
2542 if (tracemark_fd < 0) 2388 if (tracemark_fd < 0)
2543 return; 2389 return;
2544 /* write the tracemark message */ 2390 /* write the tracemark message */
2545 write(tracemark_fd, str, strlen(str)) 2391 write(tracemark_fd, str, strlen(str));
2546 } 2392 }
2547 2393
2548 And later add something like:: 2394 And later add something like::
2549 2395
2550 traceputs("start"); 2396 traceputs("start");
2551 clock_nanosleep(...); 2397 clock_nanosleep(...);
2552 traceputs("end"); 2398 traceputs("end");
2553 2399
2554 We can make a histogram from this:: 2400 We can make a histogram from this::
2555 2401
2556 # cd /sys/kernel/tracing 2402 # cd /sys/kernel/tracing
2557 # echo 'latency u64 lat' > synthetic_events 2403 # echo 'latency u64 lat' > synthetic_events
2558 # echo 'hist:keys=common_pid:ts0=common_time 2404 # echo 'hist:keys=common_pid:ts0=common_timestamp.usecs if buf == "start"' > events/ftrace/print/trigger
2559 # echo 'hist:keys=common_pid:lat=common_time 2405 # echo 'hist:keys=common_pid:lat=common_timestamp.usecs-$ts0:onmatch(ftrace.print).latency($lat) if buf == "end"' >> events/ftrace/print/trigger
2560 # echo 'hist:keys=lat,common_pid:sort=lat' > 2406 # echo 'hist:keys=lat,common_pid:sort=lat' > events/synthetic/latency/trigger
2561 2407
2562 The above created a synthetic event called "l 2408 The above created a synthetic event called "latency" and two histograms
2563 against the trace_marker, one gets triggered 2409 against the trace_marker, one gets triggered when "start" is written into the
2564 trace_marker file and the other when "end" is 2410 trace_marker file and the other when "end" is written. If the pids match, then
2565 it will call the "latency" synthetic event wi 2411 it will call the "latency" synthetic event with the calculated latency as its
2566 parameter. Finally, a histogram is added to t 2412 parameter. Finally, a histogram is added to the latency synthetic event to
2567 record the calculated latency along with the 2413 record the calculated latency along with the pid.
2568 2414
2569 Now running cyclictest with:: 2415 Now running cyclictest with::
2570 2416
2571 # ./cyclictest -p80 -d0 -i250 -n -a -t --tra 2417 # ./cyclictest -p80 -d0 -i250 -n -a -t --tracemark -b 1000
2572 2418
2573 -p80 : run threads at priority 80 2419 -p80 : run threads at priority 80
2574 -d0 : have all threads run at the same int 2420 -d0 : have all threads run at the same interval
2575 -i250 : start the interval at 250 microsecon 2421 -i250 : start the interval at 250 microseconds (all threads will do this)
2576 -n : sleep with nanosleep 2422 -n : sleep with nanosleep
2577 -a : affine all threads to a separate CPU 2423 -a : affine all threads to a separate CPU
2578 -t : one thread per available CPU 2424 -t : one thread per available CPU
2579 --tracemark : enable trace mark writing 2425 --tracemark : enable trace mark writing
2580 -b 1000 : stop if any latency is greater tha 2426 -b 1000 : stop if any latency is greater than 1000 microseconds
2581 2427
2582 Note, the -b 1000 is used just to make --trac 2428 Note, the -b 1000 is used just to make --tracemark available.
2583 2429
2584 Then we can see the histogram created by this 2430 Then we can see the histogram created by this with::
2585 2431
2586 # cat events/synthetic/latency/hist 2432 # cat events/synthetic/latency/hist
2587 # event histogram 2433 # event histogram
2588 # 2434 #
2589 # trigger info: hist:keys=lat,common_pid:val 2435 # trigger info: hist:keys=lat,common_pid:vals=hitcount:sort=lat:size=2048 [active]
2590 # 2436 #
2591 2437
2592 { lat: 107, common_pid: 2039 } 2438 { lat: 107, common_pid: 2039 } hitcount: 1
2593 { lat: 122, common_pid: 2041 } 2439 { lat: 122, common_pid: 2041 } hitcount: 1
2594 { lat: 166, common_pid: 2039 } 2440 { lat: 166, common_pid: 2039 } hitcount: 1
2595 { lat: 174, common_pid: 2039 } 2441 { lat: 174, common_pid: 2039 } hitcount: 1
2596 { lat: 194, common_pid: 2041 } 2442 { lat: 194, common_pid: 2041 } hitcount: 1
2597 { lat: 196, common_pid: 2036 } 2443 { lat: 196, common_pid: 2036 } hitcount: 1
2598 { lat: 197, common_pid: 2038 } 2444 { lat: 197, common_pid: 2038 } hitcount: 1
2599 { lat: 198, common_pid: 2039 } 2445 { lat: 198, common_pid: 2039 } hitcount: 1
2600 { lat: 199, common_pid: 2039 } 2446 { lat: 199, common_pid: 2039 } hitcount: 1
2601 { lat: 200, common_pid: 2041 } 2447 { lat: 200, common_pid: 2041 } hitcount: 1
2602 { lat: 201, common_pid: 2039 } 2448 { lat: 201, common_pid: 2039 } hitcount: 2
2603 { lat: 202, common_pid: 2038 } 2449 { lat: 202, common_pid: 2038 } hitcount: 1
2604 { lat: 202, common_pid: 2043 } 2450 { lat: 202, common_pid: 2043 } hitcount: 1
2605 { lat: 203, common_pid: 2039 } 2451 { lat: 203, common_pid: 2039 } hitcount: 1
2606 { lat: 203, common_pid: 2036 } 2452 { lat: 203, common_pid: 2036 } hitcount: 1
2607 { lat: 203, common_pid: 2041 } 2453 { lat: 203, common_pid: 2041 } hitcount: 1
2608 { lat: 206, common_pid: 2038 } 2454 { lat: 206, common_pid: 2038 } hitcount: 2
2609 { lat: 207, common_pid: 2039 } 2455 { lat: 207, common_pid: 2039 } hitcount: 1
2610 { lat: 207, common_pid: 2036 } 2456 { lat: 207, common_pid: 2036 } hitcount: 1
2611 { lat: 208, common_pid: 2040 } 2457 { lat: 208, common_pid: 2040 } hitcount: 1
2612 { lat: 209, common_pid: 2043 } 2458 { lat: 209, common_pid: 2043 } hitcount: 1
2613 { lat: 210, common_pid: 2039 } 2459 { lat: 210, common_pid: 2039 } hitcount: 1
2614 { lat: 211, common_pid: 2039 } 2460 { lat: 211, common_pid: 2039 } hitcount: 4
2615 { lat: 212, common_pid: 2043 } 2461 { lat: 212, common_pid: 2043 } hitcount: 1
2616 { lat: 212, common_pid: 2039 } 2462 { lat: 212, common_pid: 2039 } hitcount: 2
2617 { lat: 213, common_pid: 2039 } 2463 { lat: 213, common_pid: 2039 } hitcount: 1
2618 { lat: 214, common_pid: 2038 } 2464 { lat: 214, common_pid: 2038 } hitcount: 1
2619 { lat: 214, common_pid: 2039 } 2465 { lat: 214, common_pid: 2039 } hitcount: 2
2620 { lat: 214, common_pid: 2042 } 2466 { lat: 214, common_pid: 2042 } hitcount: 1
2621 { lat: 215, common_pid: 2039 } 2467 { lat: 215, common_pid: 2039 } hitcount: 1
2622 { lat: 217, common_pid: 2036 } 2468 { lat: 217, common_pid: 2036 } hitcount: 1
2623 { lat: 217, common_pid: 2040 } 2469 { lat: 217, common_pid: 2040 } hitcount: 1
2624 { lat: 217, common_pid: 2039 } 2470 { lat: 217, common_pid: 2039 } hitcount: 1
2625 { lat: 218, common_pid: 2039 } 2471 { lat: 218, common_pid: 2039 } hitcount: 6
2626 { lat: 219, common_pid: 2039 } 2472 { lat: 219, common_pid: 2039 } hitcount: 9
2627 { lat: 220, common_pid: 2039 } 2473 { lat: 220, common_pid: 2039 } hitcount: 11
2628 { lat: 221, common_pid: 2039 } 2474 { lat: 221, common_pid: 2039 } hitcount: 5
2629 { lat: 221, common_pid: 2042 } 2475 { lat: 221, common_pid: 2042 } hitcount: 1
2630 { lat: 222, common_pid: 2039 } 2476 { lat: 222, common_pid: 2039 } hitcount: 7
2631 { lat: 223, common_pid: 2036 } 2477 { lat: 223, common_pid: 2036 } hitcount: 1
2632 { lat: 223, common_pid: 2039 } 2478 { lat: 223, common_pid: 2039 } hitcount: 3
2633 { lat: 224, common_pid: 2039 } 2479 { lat: 224, common_pid: 2039 } hitcount: 4
2634 { lat: 224, common_pid: 2037 } 2480 { lat: 224, common_pid: 2037 } hitcount: 1
2635 { lat: 224, common_pid: 2036 } 2481 { lat: 224, common_pid: 2036 } hitcount: 2
2636 { lat: 225, common_pid: 2039 } 2482 { lat: 225, common_pid: 2039 } hitcount: 5
2637 { lat: 225, common_pid: 2042 } 2483 { lat: 225, common_pid: 2042 } hitcount: 1
2638 { lat: 226, common_pid: 2039 } 2484 { lat: 226, common_pid: 2039 } hitcount: 7
2639 { lat: 226, common_pid: 2036 } 2485 { lat: 226, common_pid: 2036 } hitcount: 4
2640 { lat: 227, common_pid: 2039 } 2486 { lat: 227, common_pid: 2039 } hitcount: 6
2641 { lat: 227, common_pid: 2036 } 2487 { lat: 227, common_pid: 2036 } hitcount: 12
2642 { lat: 227, common_pid: 2043 } 2488 { lat: 227, common_pid: 2043 } hitcount: 1
2643 { lat: 228, common_pid: 2039 } 2489 { lat: 228, common_pid: 2039 } hitcount: 7
2644 { lat: 228, common_pid: 2036 } 2490 { lat: 228, common_pid: 2036 } hitcount: 14
2645 { lat: 229, common_pid: 2039 } 2491 { lat: 229, common_pid: 2039 } hitcount: 9
2646 { lat: 229, common_pid: 2036 } 2492 { lat: 229, common_pid: 2036 } hitcount: 8
2647 { lat: 229, common_pid: 2038 } 2493 { lat: 229, common_pid: 2038 } hitcount: 1
2648 { lat: 230, common_pid: 2039 } 2494 { lat: 230, common_pid: 2039 } hitcount: 11
2649 { lat: 230, common_pid: 2036 } 2495 { lat: 230, common_pid: 2036 } hitcount: 6
2650 { lat: 230, common_pid: 2043 } 2496 { lat: 230, common_pid: 2043 } hitcount: 1
2651 { lat: 230, common_pid: 2042 } 2497 { lat: 230, common_pid: 2042 } hitcount: 2
2652 { lat: 231, common_pid: 2041 } 2498 { lat: 231, common_pid: 2041 } hitcount: 1
2653 { lat: 231, common_pid: 2036 } 2499 { lat: 231, common_pid: 2036 } hitcount: 6
2654 { lat: 231, common_pid: 2043 } 2500 { lat: 231, common_pid: 2043 } hitcount: 1
2655 { lat: 231, common_pid: 2039 } 2501 { lat: 231, common_pid: 2039 } hitcount: 8
2656 { lat: 232, common_pid: 2037 } 2502 { lat: 232, common_pid: 2037 } hitcount: 1
2657 { lat: 232, common_pid: 2039 } 2503 { lat: 232, common_pid: 2039 } hitcount: 6
2658 { lat: 232, common_pid: 2040 } 2504 { lat: 232, common_pid: 2040 } hitcount: 2
2659 { lat: 232, common_pid: 2036 } 2505 { lat: 232, common_pid: 2036 } hitcount: 5
2660 { lat: 232, common_pid: 2043 } 2506 { lat: 232, common_pid: 2043 } hitcount: 1
2661 { lat: 233, common_pid: 2036 } 2507 { lat: 233, common_pid: 2036 } hitcount: 5
2662 { lat: 233, common_pid: 2039 } 2508 { lat: 233, common_pid: 2039 } hitcount: 11
2663 { lat: 234, common_pid: 2039 } 2509 { lat: 234, common_pid: 2039 } hitcount: 4
2664 { lat: 234, common_pid: 2038 } 2510 { lat: 234, common_pid: 2038 } hitcount: 2
2665 { lat: 234, common_pid: 2043 } 2511 { lat: 234, common_pid: 2043 } hitcount: 2
2666 { lat: 234, common_pid: 2036 } 2512 { lat: 234, common_pid: 2036 } hitcount: 11
2667 { lat: 234, common_pid: 2040 } 2513 { lat: 234, common_pid: 2040 } hitcount: 1
2668 { lat: 235, common_pid: 2037 } 2514 { lat: 235, common_pid: 2037 } hitcount: 2
2669 { lat: 235, common_pid: 2036 } 2515 { lat: 235, common_pid: 2036 } hitcount: 8
2670 { lat: 235, common_pid: 2043 } 2516 { lat: 235, common_pid: 2043 } hitcount: 2
2671 { lat: 235, common_pid: 2039 } 2517 { lat: 235, common_pid: 2039 } hitcount: 5
2672 { lat: 235, common_pid: 2042 } 2518 { lat: 235, common_pid: 2042 } hitcount: 2
2673 { lat: 235, common_pid: 2040 } 2519 { lat: 235, common_pid: 2040 } hitcount: 4
2674 { lat: 235, common_pid: 2041 } 2520 { lat: 235, common_pid: 2041 } hitcount: 1
2675 { lat: 236, common_pid: 2036 } 2521 { lat: 236, common_pid: 2036 } hitcount: 7
2676 { lat: 236, common_pid: 2037 } 2522 { lat: 236, common_pid: 2037 } hitcount: 1
2677 { lat: 236, common_pid: 2041 } 2523 { lat: 236, common_pid: 2041 } hitcount: 5
2678 { lat: 236, common_pid: 2039 } 2524 { lat: 236, common_pid: 2039 } hitcount: 3
2679 { lat: 236, common_pid: 2043 } 2525 { lat: 236, common_pid: 2043 } hitcount: 9
2680 { lat: 236, common_pid: 2040 } 2526 { lat: 236, common_pid: 2040 } hitcount: 7
2681 { lat: 237, common_pid: 2037 } 2527 { lat: 237, common_pid: 2037 } hitcount: 1
2682 { lat: 237, common_pid: 2040 } 2528 { lat: 237, common_pid: 2040 } hitcount: 1
2683 { lat: 237, common_pid: 2036 } 2529 { lat: 237, common_pid: 2036 } hitcount: 9
2684 { lat: 237, common_pid: 2039 } 2530 { lat: 237, common_pid: 2039 } hitcount: 3
2685 { lat: 237, common_pid: 2043 } 2531 { lat: 237, common_pid: 2043 } hitcount: 8
2686 { lat: 237, common_pid: 2042 } 2532 { lat: 237, common_pid: 2042 } hitcount: 2
2687 { lat: 237, common_pid: 2041 } 2533 { lat: 237, common_pid: 2041 } hitcount: 2
2688 { lat: 238, common_pid: 2043 } 2534 { lat: 238, common_pid: 2043 } hitcount: 10
2689 { lat: 238, common_pid: 2040 } 2535 { lat: 238, common_pid: 2040 } hitcount: 1
2690 { lat: 238, common_pid: 2037 } 2536 { lat: 238, common_pid: 2037 } hitcount: 9
2691 { lat: 238, common_pid: 2038 } 2537 { lat: 238, common_pid: 2038 } hitcount: 1
2692 { lat: 238, common_pid: 2039 } 2538 { lat: 238, common_pid: 2039 } hitcount: 1
2693 { lat: 238, common_pid: 2042 } 2539 { lat: 238, common_pid: 2042 } hitcount: 3
2694 { lat: 238, common_pid: 2036 } 2540 { lat: 238, common_pid: 2036 } hitcount: 7
2695 { lat: 239, common_pid: 2041 } 2541 { lat: 239, common_pid: 2041 } hitcount: 1
2696 { lat: 239, common_pid: 2043 } 2542 { lat: 239, common_pid: 2043 } hitcount: 11
2697 { lat: 239, common_pid: 2037 } 2543 { lat: 239, common_pid: 2037 } hitcount: 11
2698 { lat: 239, common_pid: 2038 } 2544 { lat: 239, common_pid: 2038 } hitcount: 6
2699 { lat: 239, common_pid: 2036 } 2545 { lat: 239, common_pid: 2036 } hitcount: 7
2700 { lat: 239, common_pid: 2040 } 2546 { lat: 239, common_pid: 2040 } hitcount: 1
2701 { lat: 239, common_pid: 2042 } 2547 { lat: 239, common_pid: 2042 } hitcount: 9
2702 { lat: 240, common_pid: 2037 } 2548 { lat: 240, common_pid: 2037 } hitcount: 29
2703 { lat: 240, common_pid: 2043 } 2549 { lat: 240, common_pid: 2043 } hitcount: 15
2704 { lat: 240, common_pid: 2040 } 2550 { lat: 240, common_pid: 2040 } hitcount: 44
2705 { lat: 240, common_pid: 2039 } 2551 { lat: 240, common_pid: 2039 } hitcount: 1
2706 { lat: 240, common_pid: 2041 } 2552 { lat: 240, common_pid: 2041 } hitcount: 2
2707 { lat: 240, common_pid: 2038 } 2553 { lat: 240, common_pid: 2038 } hitcount: 1
2708 { lat: 240, common_pid: 2036 } 2554 { lat: 240, common_pid: 2036 } hitcount: 10
2709 { lat: 240, common_pid: 2042 } 2555 { lat: 240, common_pid: 2042 } hitcount: 13
2710 { lat: 241, common_pid: 2036 } 2556 { lat: 241, common_pid: 2036 } hitcount: 21
2711 { lat: 241, common_pid: 2041 } 2557 { lat: 241, common_pid: 2041 } hitcount: 36
2712 { lat: 241, common_pid: 2037 } 2558 { lat: 241, common_pid: 2037 } hitcount: 34
2713 { lat: 241, common_pid: 2042 } 2559 { lat: 241, common_pid: 2042 } hitcount: 14
2714 { lat: 241, common_pid: 2040 } 2560 { lat: 241, common_pid: 2040 } hitcount: 94
2715 { lat: 241, common_pid: 2039 } 2561 { lat: 241, common_pid: 2039 } hitcount: 12
2716 { lat: 241, common_pid: 2038 } 2562 { lat: 241, common_pid: 2038 } hitcount: 2
2717 { lat: 241, common_pid: 2043 } 2563 { lat: 241, common_pid: 2043 } hitcount: 28
2718 { lat: 242, common_pid: 2040 } 2564 { lat: 242, common_pid: 2040 } hitcount: 109
2719 { lat: 242, common_pid: 2041 } 2565 { lat: 242, common_pid: 2041 } hitcount: 506
2720 { lat: 242, common_pid: 2039 } 2566 { lat: 242, common_pid: 2039 } hitcount: 155
2721 { lat: 242, common_pid: 2042 } 2567 { lat: 242, common_pid: 2042 } hitcount: 21
2722 { lat: 242, common_pid: 2037 } 2568 { lat: 242, common_pid: 2037 } hitcount: 52
2723 { lat: 242, common_pid: 2043 } 2569 { lat: 242, common_pid: 2043 } hitcount: 21
2724 { lat: 242, common_pid: 2036 } 2570 { lat: 242, common_pid: 2036 } hitcount: 16
2725 { lat: 242, common_pid: 2038 } 2571 { lat: 242, common_pid: 2038 } hitcount: 156
2726 { lat: 243, common_pid: 2037 } 2572 { lat: 243, common_pid: 2037 } hitcount: 46
2727 { lat: 243, common_pid: 2039 } 2573 { lat: 243, common_pid: 2039 } hitcount: 40
2728 { lat: 243, common_pid: 2042 } 2574 { lat: 243, common_pid: 2042 } hitcount: 119
2729 { lat: 243, common_pid: 2041 } 2575 { lat: 243, common_pid: 2041 } hitcount: 611
2730 { lat: 243, common_pid: 2036 } 2576 { lat: 243, common_pid: 2036 } hitcount: 69
2731 { lat: 243, common_pid: 2038 } 2577 { lat: 243, common_pid: 2038 } hitcount: 784
2732 { lat: 243, common_pid: 2040 } 2578 { lat: 243, common_pid: 2040 } hitcount: 323
2733 { lat: 243, common_pid: 2043 } 2579 { lat: 243, common_pid: 2043 } hitcount: 14
2734 { lat: 244, common_pid: 2043 } 2580 { lat: 244, common_pid: 2043 } hitcount: 35
2735 { lat: 244, common_pid: 2042 } 2581 { lat: 244, common_pid: 2042 } hitcount: 305
2736 { lat: 244, common_pid: 2039 } 2582 { lat: 244, common_pid: 2039 } hitcount: 8
2737 { lat: 244, common_pid: 2040 } 2583 { lat: 244, common_pid: 2040 } hitcount: 4515
2738 { lat: 244, common_pid: 2038 } 2584 { lat: 244, common_pid: 2038 } hitcount: 371
2739 { lat: 244, common_pid: 2037 } 2585 { lat: 244, common_pid: 2037 } hitcount: 31
2740 { lat: 244, common_pid: 2036 } 2586 { lat: 244, common_pid: 2036 } hitcount: 114
2741 { lat: 244, common_pid: 2041 } 2587 { lat: 244, common_pid: 2041 } hitcount: 3396
2742 { lat: 245, common_pid: 2036 } 2588 { lat: 245, common_pid: 2036 } hitcount: 700
2743 { lat: 245, common_pid: 2041 } 2589 { lat: 245, common_pid: 2041 } hitcount: 2772
2744 { lat: 245, common_pid: 2037 } 2590 { lat: 245, common_pid: 2037 } hitcount: 268
2745 { lat: 245, common_pid: 2039 } 2591 { lat: 245, common_pid: 2039 } hitcount: 472
2746 { lat: 245, common_pid: 2038 } 2592 { lat: 245, common_pid: 2038 } hitcount: 2758
2747 { lat: 245, common_pid: 2042 } 2593 { lat: 245, common_pid: 2042 } hitcount: 3833
2748 { lat: 245, common_pid: 2040 } 2594 { lat: 245, common_pid: 2040 } hitcount: 3105
2749 { lat: 245, common_pid: 2043 } 2595 { lat: 245, common_pid: 2043 } hitcount: 645
2750 { lat: 246, common_pid: 2038 } 2596 { lat: 246, common_pid: 2038 } hitcount: 3451
2751 { lat: 246, common_pid: 2041 } 2597 { lat: 246, common_pid: 2041 } hitcount: 142
2752 { lat: 246, common_pid: 2037 } 2598 { lat: 246, common_pid: 2037 } hitcount: 5101
2753 { lat: 246, common_pid: 2040 } 2599 { lat: 246, common_pid: 2040 } hitcount: 68
2754 { lat: 246, common_pid: 2043 } 2600 { lat: 246, common_pid: 2043 } hitcount: 5099
2755 { lat: 246, common_pid: 2039 } 2601 { lat: 246, common_pid: 2039 } hitcount: 5608
2756 { lat: 246, common_pid: 2042 } 2602 { lat: 246, common_pid: 2042 } hitcount: 3723
2757 { lat: 246, common_pid: 2036 } 2603 { lat: 246, common_pid: 2036 } hitcount: 4738
2758 { lat: 247, common_pid: 2042 } 2604 { lat: 247, common_pid: 2042 } hitcount: 312
2759 { lat: 247, common_pid: 2043 } 2605 { lat: 247, common_pid: 2043 } hitcount: 2385
2760 { lat: 247, common_pid: 2041 } 2606 { lat: 247, common_pid: 2041 } hitcount: 452
2761 { lat: 247, common_pid: 2038 } 2607 { lat: 247, common_pid: 2038 } hitcount: 792
2762 { lat: 247, common_pid: 2040 } 2608 { lat: 247, common_pid: 2040 } hitcount: 78
2763 { lat: 247, common_pid: 2036 } 2609 { lat: 247, common_pid: 2036 } hitcount: 2375
2764 { lat: 247, common_pid: 2039 } 2610 { lat: 247, common_pid: 2039 } hitcount: 1834
2765 { lat: 247, common_pid: 2037 } 2611 { lat: 247, common_pid: 2037 } hitcount: 2655
2766 { lat: 248, common_pid: 2037 } 2612 { lat: 248, common_pid: 2037 } hitcount: 36
2767 { lat: 248, common_pid: 2042 } 2613 { lat: 248, common_pid: 2042 } hitcount: 11
2768 { lat: 248, common_pid: 2038 } 2614 { lat: 248, common_pid: 2038 } hitcount: 122
2769 { lat: 248, common_pid: 2036 } 2615 { lat: 248, common_pid: 2036 } hitcount: 135
2770 { lat: 248, common_pid: 2039 } 2616 { lat: 248, common_pid: 2039 } hitcount: 26
2771 { lat: 248, common_pid: 2041 } 2617 { lat: 248, common_pid: 2041 } hitcount: 503
2772 { lat: 248, common_pid: 2043 } 2618 { lat: 248, common_pid: 2043 } hitcount: 66
2773 { lat: 248, common_pid: 2040 } 2619 { lat: 248, common_pid: 2040 } hitcount: 46
2774 { lat: 249, common_pid: 2037 } 2620 { lat: 249, common_pid: 2037 } hitcount: 29
2775 { lat: 249, common_pid: 2038 } 2621 { lat: 249, common_pid: 2038 } hitcount: 1
2776 { lat: 249, common_pid: 2043 } 2622 { lat: 249, common_pid: 2043 } hitcount: 29
2777 { lat: 249, common_pid: 2039 } 2623 { lat: 249, common_pid: 2039 } hitcount: 8
2778 { lat: 249, common_pid: 2042 } 2624 { lat: 249, common_pid: 2042 } hitcount: 56
2779 { lat: 249, common_pid: 2040 } 2625 { lat: 249, common_pid: 2040 } hitcount: 27
2780 { lat: 249, common_pid: 2041 } 2626 { lat: 249, common_pid: 2041 } hitcount: 11
2781 { lat: 249, common_pid: 2036 } 2627 { lat: 249, common_pid: 2036 } hitcount: 27
2782 { lat: 250, common_pid: 2038 } 2628 { lat: 250, common_pid: 2038 } hitcount: 1
2783 { lat: 250, common_pid: 2036 } 2629 { lat: 250, common_pid: 2036 } hitcount: 30
2784 { lat: 250, common_pid: 2040 } 2630 { lat: 250, common_pid: 2040 } hitcount: 19
2785 { lat: 250, common_pid: 2043 } 2631 { lat: 250, common_pid: 2043 } hitcount: 22
2786 { lat: 250, common_pid: 2042 } 2632 { lat: 250, common_pid: 2042 } hitcount: 20
2787 { lat: 250, common_pid: 2041 } 2633 { lat: 250, common_pid: 2041 } hitcount: 1
2788 { lat: 250, common_pid: 2039 } 2634 { lat: 250, common_pid: 2039 } hitcount: 6
2789 { lat: 250, common_pid: 2037 } 2635 { lat: 250, common_pid: 2037 } hitcount: 48
2790 { lat: 251, common_pid: 2037 } 2636 { lat: 251, common_pid: 2037 } hitcount: 43
2791 { lat: 251, common_pid: 2039 } 2637 { lat: 251, common_pid: 2039 } hitcount: 1
2792 { lat: 251, common_pid: 2036 } 2638 { lat: 251, common_pid: 2036 } hitcount: 12
2793 { lat: 251, common_pid: 2042 } 2639 { lat: 251, common_pid: 2042 } hitcount: 2
2794 { lat: 251, common_pid: 2041 } 2640 { lat: 251, common_pid: 2041 } hitcount: 1
2795 { lat: 251, common_pid: 2043 } 2641 { lat: 251, common_pid: 2043 } hitcount: 15
2796 { lat: 251, common_pid: 2040 } 2642 { lat: 251, common_pid: 2040 } hitcount: 3
2797 { lat: 252, common_pid: 2040 } 2643 { lat: 252, common_pid: 2040 } hitcount: 1
2798 { lat: 252, common_pid: 2036 } 2644 { lat: 252, common_pid: 2036 } hitcount: 12
2799 { lat: 252, common_pid: 2037 } 2645 { lat: 252, common_pid: 2037 } hitcount: 21
2800 { lat: 252, common_pid: 2043 } 2646 { lat: 252, common_pid: 2043 } hitcount: 14
2801 { lat: 253, common_pid: 2037 } 2647 { lat: 253, common_pid: 2037 } hitcount: 21
2802 { lat: 253, common_pid: 2039 } 2648 { lat: 253, common_pid: 2039 } hitcount: 2
2803 { lat: 253, common_pid: 2036 } 2649 { lat: 253, common_pid: 2036 } hitcount: 9
2804 { lat: 253, common_pid: 2043 } 2650 { lat: 253, common_pid: 2043 } hitcount: 6
2805 { lat: 253, common_pid: 2040 } 2651 { lat: 253, common_pid: 2040 } hitcount: 1
2806 { lat: 254, common_pid: 2036 } 2652 { lat: 254, common_pid: 2036 } hitcount: 8
2807 { lat: 254, common_pid: 2043 } 2653 { lat: 254, common_pid: 2043 } hitcount: 3
2808 { lat: 254, common_pid: 2041 } 2654 { lat: 254, common_pid: 2041 } hitcount: 1
2809 { lat: 254, common_pid: 2042 } 2655 { lat: 254, common_pid: 2042 } hitcount: 1
2810 { lat: 254, common_pid: 2039 } 2656 { lat: 254, common_pid: 2039 } hitcount: 1
2811 { lat: 254, common_pid: 2037 } 2657 { lat: 254, common_pid: 2037 } hitcount: 12
2812 { lat: 255, common_pid: 2043 } 2658 { lat: 255, common_pid: 2043 } hitcount: 1
2813 { lat: 255, common_pid: 2037 } 2659 { lat: 255, common_pid: 2037 } hitcount: 2
2814 { lat: 255, common_pid: 2036 } 2660 { lat: 255, common_pid: 2036 } hitcount: 2
2815 { lat: 255, common_pid: 2039 } 2661 { lat: 255, common_pid: 2039 } hitcount: 8
2816 { lat: 256, common_pid: 2043 } 2662 { lat: 256, common_pid: 2043 } hitcount: 1
2817 { lat: 256, common_pid: 2036 } 2663 { lat: 256, common_pid: 2036 } hitcount: 4
2818 { lat: 256, common_pid: 2039 } 2664 { lat: 256, common_pid: 2039 } hitcount: 6
2819 { lat: 257, common_pid: 2039 } 2665 { lat: 257, common_pid: 2039 } hitcount: 5
2820 { lat: 257, common_pid: 2036 } 2666 { lat: 257, common_pid: 2036 } hitcount: 4
2821 { lat: 258, common_pid: 2039 } 2667 { lat: 258, common_pid: 2039 } hitcount: 5
2822 { lat: 258, common_pid: 2036 } 2668 { lat: 258, common_pid: 2036 } hitcount: 2
2823 { lat: 259, common_pid: 2036 } 2669 { lat: 259, common_pid: 2036 } hitcount: 7
2824 { lat: 259, common_pid: 2039 } 2670 { lat: 259, common_pid: 2039 } hitcount: 7
2825 { lat: 260, common_pid: 2036 } 2671 { lat: 260, common_pid: 2036 } hitcount: 8
2826 { lat: 260, common_pid: 2039 } 2672 { lat: 260, common_pid: 2039 } hitcount: 6
2827 { lat: 261, common_pid: 2036 } 2673 { lat: 261, common_pid: 2036 } hitcount: 5
2828 { lat: 261, common_pid: 2039 } 2674 { lat: 261, common_pid: 2039 } hitcount: 7
2829 { lat: 262, common_pid: 2039 } 2675 { lat: 262, common_pid: 2039 } hitcount: 5
2830 { lat: 262, common_pid: 2036 } 2676 { lat: 262, common_pid: 2036 } hitcount: 5
2831 { lat: 263, common_pid: 2039 } 2677 { lat: 263, common_pid: 2039 } hitcount: 7
2832 { lat: 263, common_pid: 2036 } 2678 { lat: 263, common_pid: 2036 } hitcount: 7
2833 { lat: 264, common_pid: 2039 } 2679 { lat: 264, common_pid: 2039 } hitcount: 9
2834 { lat: 264, common_pid: 2036 } 2680 { lat: 264, common_pid: 2036 } hitcount: 9
2835 { lat: 265, common_pid: 2036 } 2681 { lat: 265, common_pid: 2036 } hitcount: 5
2836 { lat: 265, common_pid: 2039 } 2682 { lat: 265, common_pid: 2039 } hitcount: 1
2837 { lat: 266, common_pid: 2036 } 2683 { lat: 266, common_pid: 2036 } hitcount: 1
2838 { lat: 266, common_pid: 2039 } 2684 { lat: 266, common_pid: 2039 } hitcount: 3
2839 { lat: 267, common_pid: 2036 } 2685 { lat: 267, common_pid: 2036 } hitcount: 1
2840 { lat: 267, common_pid: 2039 } 2686 { lat: 267, common_pid: 2039 } hitcount: 3
2841 { lat: 268, common_pid: 2036 } 2687 { lat: 268, common_pid: 2036 } hitcount: 1
2842 { lat: 268, common_pid: 2039 } 2688 { lat: 268, common_pid: 2039 } hitcount: 6
2843 { lat: 269, common_pid: 2036 } 2689 { lat: 269, common_pid: 2036 } hitcount: 1
2844 { lat: 269, common_pid: 2043 } 2690 { lat: 269, common_pid: 2043 } hitcount: 1
2845 { lat: 269, common_pid: 2039 } 2691 { lat: 269, common_pid: 2039 } hitcount: 2
2846 { lat: 270, common_pid: 2040 } 2692 { lat: 270, common_pid: 2040 } hitcount: 1
2847 { lat: 270, common_pid: 2039 } 2693 { lat: 270, common_pid: 2039 } hitcount: 6
2848 { lat: 271, common_pid: 2041 } 2694 { lat: 271, common_pid: 2041 } hitcount: 1
2849 { lat: 271, common_pid: 2039 } 2695 { lat: 271, common_pid: 2039 } hitcount: 5
2850 { lat: 272, common_pid: 2039 } 2696 { lat: 272, common_pid: 2039 } hitcount: 10
2851 { lat: 273, common_pid: 2039 } 2697 { lat: 273, common_pid: 2039 } hitcount: 8
2852 { lat: 274, common_pid: 2039 } 2698 { lat: 274, common_pid: 2039 } hitcount: 2
2853 { lat: 275, common_pid: 2039 } 2699 { lat: 275, common_pid: 2039 } hitcount: 1
2854 { lat: 276, common_pid: 2039 } 2700 { lat: 276, common_pid: 2039 } hitcount: 2
2855 { lat: 276, common_pid: 2037 } 2701 { lat: 276, common_pid: 2037 } hitcount: 1
2856 { lat: 276, common_pid: 2038 } 2702 { lat: 276, common_pid: 2038 } hitcount: 1
2857 { lat: 277, common_pid: 2039 } 2703 { lat: 277, common_pid: 2039 } hitcount: 1
2858 { lat: 277, common_pid: 2042 } 2704 { lat: 277, common_pid: 2042 } hitcount: 1
2859 { lat: 278, common_pid: 2039 } 2705 { lat: 278, common_pid: 2039 } hitcount: 1
2860 { lat: 279, common_pid: 2039 } 2706 { lat: 279, common_pid: 2039 } hitcount: 4
2861 { lat: 279, common_pid: 2043 } 2707 { lat: 279, common_pid: 2043 } hitcount: 1
2862 { lat: 280, common_pid: 2039 } 2708 { lat: 280, common_pid: 2039 } hitcount: 3
2863 { lat: 283, common_pid: 2036 } 2709 { lat: 283, common_pid: 2036 } hitcount: 2
2864 { lat: 284, common_pid: 2039 } 2710 { lat: 284, common_pid: 2039 } hitcount: 1
2865 { lat: 284, common_pid: 2043 } 2711 { lat: 284, common_pid: 2043 } hitcount: 1
2866 { lat: 288, common_pid: 2039 } 2712 { lat: 288, common_pid: 2039 } hitcount: 1
2867 { lat: 289, common_pid: 2039 } 2713 { lat: 289, common_pid: 2039 } hitcount: 1
2868 { lat: 300, common_pid: 2039 } 2714 { lat: 300, common_pid: 2039 } hitcount: 1
2869 { lat: 384, common_pid: 2039 } 2715 { lat: 384, common_pid: 2039 } hitcount: 1
2870 2716
2871 Totals: 2717 Totals:
2872 Hits: 67625 2718 Hits: 67625
2873 Entries: 278 2719 Entries: 278
2874 Dropped: 0 2720 Dropped: 0
2875 2721
2876 Note, the writes are around the sleep, so ide 2722 Note, the writes are around the sleep, so ideally they will all be of 250
2877 microseconds. If you are wondering how there 2723 microseconds. If you are wondering how there are several that are under
2878 250 microseconds, that is because the way cyc 2724 250 microseconds, that is because the way cyclictest works, is if one
2879 iteration comes in late, the next one will se 2725 iteration comes in late, the next one will set the timer to wake up less that
2880 250. That is, if an iteration came in 50 micr 2726 250. That is, if an iteration came in 50 microseconds late, the next wake up
2881 will be at 200 microseconds. 2727 will be at 200 microseconds.
2882 2728
2883 But this could easily be done in userspace. T 2729 But this could easily be done in userspace. To make this even more
2884 interesting, we can mix the histogram between 2730 interesting, we can mix the histogram between events that happened in the
2885 kernel with trace_marker:: 2731 kernel with trace_marker::
2886 2732
2887 # cd /sys/kernel/tracing 2733 # cd /sys/kernel/tracing
2888 # echo 'latency u64 lat' > synthetic_events 2734 # echo 'latency u64 lat' > synthetic_events
2889 # echo 'hist:keys=pid:ts0=common_timestamp.u 2735 # echo 'hist:keys=pid:ts0=common_timestamp.usecs' > events/sched/sched_waking/trigger
2890 # echo 'hist:keys=common_pid:lat=common_time 2736 # echo 'hist:keys=common_pid:lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_waking).latency($lat) if buf == "end"' > events/ftrace/print/trigger
2891 # echo 'hist:keys=lat,common_pid:sort=lat' > 2737 # echo 'hist:keys=lat,common_pid:sort=lat' > events/synthetic/latency/trigger
2892 2738
2893 The difference this time is that instead of u 2739 The difference this time is that instead of using the trace_marker to start
2894 the latency, the sched_waking event is used, 2740 the latency, the sched_waking event is used, matching the common_pid for the
2895 trace_marker write with the pid that is being 2741 trace_marker write with the pid that is being woken by sched_waking.
2896 2742
2897 After running cyclictest again with the same 2743 After running cyclictest again with the same parameters, we now have::
2898 2744
2899 # cat events/synthetic/latency/hist 2745 # cat events/synthetic/latency/hist
2900 # event histogram 2746 # event histogram
2901 # 2747 #
2902 # trigger info: hist:keys=lat,common_pid:val 2748 # trigger info: hist:keys=lat,common_pid:vals=hitcount:sort=lat:size=2048 [active]
2903 # 2749 #
2904 2750
2905 { lat: 7, common_pid: 2302 } 2751 { lat: 7, common_pid: 2302 } hitcount: 640
2906 { lat: 7, common_pid: 2299 } 2752 { lat: 7, common_pid: 2299 } hitcount: 42
2907 { lat: 7, common_pid: 2303 } 2753 { lat: 7, common_pid: 2303 } hitcount: 18
2908 { lat: 7, common_pid: 2305 } 2754 { lat: 7, common_pid: 2305 } hitcount: 166
2909 { lat: 7, common_pid: 2306 } 2755 { lat: 7, common_pid: 2306 } hitcount: 1
2910 { lat: 7, common_pid: 2301 } 2756 { lat: 7, common_pid: 2301 } hitcount: 91
2911 { lat: 7, common_pid: 2300 } 2757 { lat: 7, common_pid: 2300 } hitcount: 17
2912 { lat: 8, common_pid: 2303 } 2758 { lat: 8, common_pid: 2303 } hitcount: 8296
2913 { lat: 8, common_pid: 2304 } 2759 { lat: 8, common_pid: 2304 } hitcount: 6864
2914 { lat: 8, common_pid: 2305 } 2760 { lat: 8, common_pid: 2305 } hitcount: 9464
2915 { lat: 8, common_pid: 2301 } 2761 { lat: 8, common_pid: 2301 } hitcount: 9213
2916 { lat: 8, common_pid: 2306 } 2762 { lat: 8, common_pid: 2306 } hitcount: 6246
2917 { lat: 8, common_pid: 2302 } 2763 { lat: 8, common_pid: 2302 } hitcount: 8797
2918 { lat: 8, common_pid: 2299 } 2764 { lat: 8, common_pid: 2299 } hitcount: 8771
2919 { lat: 8, common_pid: 2300 } 2765 { lat: 8, common_pid: 2300 } hitcount: 8119
2920 { lat: 9, common_pid: 2305 } 2766 { lat: 9, common_pid: 2305 } hitcount: 1519
2921 { lat: 9, common_pid: 2299 } 2767 { lat: 9, common_pid: 2299 } hitcount: 2346
2922 { lat: 9, common_pid: 2303 } 2768 { lat: 9, common_pid: 2303 } hitcount: 2841
2923 { lat: 9, common_pid: 2301 } 2769 { lat: 9, common_pid: 2301 } hitcount: 1846
2924 { lat: 9, common_pid: 2304 } 2770 { lat: 9, common_pid: 2304 } hitcount: 3861
2925 { lat: 9, common_pid: 2302 } 2771 { lat: 9, common_pid: 2302 } hitcount: 1210
2926 { lat: 9, common_pid: 2300 } 2772 { lat: 9, common_pid: 2300 } hitcount: 2762
2927 { lat: 9, common_pid: 2306 } 2773 { lat: 9, common_pid: 2306 } hitcount: 4247
2928 { lat: 10, common_pid: 2299 } 2774 { lat: 10, common_pid: 2299 } hitcount: 16
2929 { lat: 10, common_pid: 2306 } 2775 { lat: 10, common_pid: 2306 } hitcount: 333
2930 { lat: 10, common_pid: 2303 } 2776 { lat: 10, common_pid: 2303 } hitcount: 16
2931 { lat: 10, common_pid: 2304 } 2777 { lat: 10, common_pid: 2304 } hitcount: 168
2932 { lat: 10, common_pid: 2302 } 2778 { lat: 10, common_pid: 2302 } hitcount: 240
2933 { lat: 10, common_pid: 2301 } 2779 { lat: 10, common_pid: 2301 } hitcount: 28
2934 { lat: 10, common_pid: 2300 } 2780 { lat: 10, common_pid: 2300 } hitcount: 95
2935 { lat: 10, common_pid: 2305 } 2781 { lat: 10, common_pid: 2305 } hitcount: 18
2936 { lat: 11, common_pid: 2303 } 2782 { lat: 11, common_pid: 2303 } hitcount: 5
2937 { lat: 11, common_pid: 2305 } 2783 { lat: 11, common_pid: 2305 } hitcount: 8
2938 { lat: 11, common_pid: 2306 } 2784 { lat: 11, common_pid: 2306 } hitcount: 221
2939 { lat: 11, common_pid: 2302 } 2785 { lat: 11, common_pid: 2302 } hitcount: 76
2940 { lat: 11, common_pid: 2304 } 2786 { lat: 11, common_pid: 2304 } hitcount: 26
2941 { lat: 11, common_pid: 2300 } 2787 { lat: 11, common_pid: 2300 } hitcount: 125
2942 { lat: 11, common_pid: 2299 } 2788 { lat: 11, common_pid: 2299 } hitcount: 2
2943 { lat: 12, common_pid: 2305 } 2789 { lat: 12, common_pid: 2305 } hitcount: 3
2944 { lat: 12, common_pid: 2300 } 2790 { lat: 12, common_pid: 2300 } hitcount: 6
2945 { lat: 12, common_pid: 2306 } 2791 { lat: 12, common_pid: 2306 } hitcount: 90
2946 { lat: 12, common_pid: 2302 } 2792 { lat: 12, common_pid: 2302 } hitcount: 4
2947 { lat: 12, common_pid: 2303 } 2793 { lat: 12, common_pid: 2303 } hitcount: 1
2948 { lat: 12, common_pid: 2304 } 2794 { lat: 12, common_pid: 2304 } hitcount: 122
2949 { lat: 13, common_pid: 2300 } 2795 { lat: 13, common_pid: 2300 } hitcount: 12
2950 { lat: 13, common_pid: 2301 } 2796 { lat: 13, common_pid: 2301 } hitcount: 1
2951 { lat: 13, common_pid: 2306 } 2797 { lat: 13, common_pid: 2306 } hitcount: 32
2952 { lat: 13, common_pid: 2302 } 2798 { lat: 13, common_pid: 2302 } hitcount: 5
2953 { lat: 13, common_pid: 2305 } 2799 { lat: 13, common_pid: 2305 } hitcount: 1
2954 { lat: 13, common_pid: 2303 } 2800 { lat: 13, common_pid: 2303 } hitcount: 1
2955 { lat: 13, common_pid: 2304 } 2801 { lat: 13, common_pid: 2304 } hitcount: 61
2956 { lat: 14, common_pid: 2303 } 2802 { lat: 14, common_pid: 2303 } hitcount: 4
2957 { lat: 14, common_pid: 2306 } 2803 { lat: 14, common_pid: 2306 } hitcount: 5
2958 { lat: 14, common_pid: 2305 } 2804 { lat: 14, common_pid: 2305 } hitcount: 4
2959 { lat: 14, common_pid: 2304 } 2805 { lat: 14, common_pid: 2304 } hitcount: 62
2960 { lat: 14, common_pid: 2302 } 2806 { lat: 14, common_pid: 2302 } hitcount: 19
2961 { lat: 14, common_pid: 2300 } 2807 { lat: 14, common_pid: 2300 } hitcount: 33
2962 { lat: 14, common_pid: 2299 } 2808 { lat: 14, common_pid: 2299 } hitcount: 1
2963 { lat: 14, common_pid: 2301 } 2809 { lat: 14, common_pid: 2301 } hitcount: 4
2964 { lat: 15, common_pid: 2305 } 2810 { lat: 15, common_pid: 2305 } hitcount: 1
2965 { lat: 15, common_pid: 2302 } 2811 { lat: 15, common_pid: 2302 } hitcount: 25
2966 { lat: 15, common_pid: 2300 } 2812 { lat: 15, common_pid: 2300 } hitcount: 11
2967 { lat: 15, common_pid: 2299 } 2813 { lat: 15, common_pid: 2299 } hitcount: 5
2968 { lat: 15, common_pid: 2301 } 2814 { lat: 15, common_pid: 2301 } hitcount: 1
2969 { lat: 15, common_pid: 2304 } 2815 { lat: 15, common_pid: 2304 } hitcount: 8
2970 { lat: 15, common_pid: 2303 } 2816 { lat: 15, common_pid: 2303 } hitcount: 1
2971 { lat: 15, common_pid: 2306 } 2817 { lat: 15, common_pid: 2306 } hitcount: 6
2972 { lat: 16, common_pid: 2302 } 2818 { lat: 16, common_pid: 2302 } hitcount: 31
2973 { lat: 16, common_pid: 2306 } 2819 { lat: 16, common_pid: 2306 } hitcount: 3
2974 { lat: 16, common_pid: 2300 } 2820 { lat: 16, common_pid: 2300 } hitcount: 5
2975 { lat: 17, common_pid: 2302 } 2821 { lat: 17, common_pid: 2302 } hitcount: 6
2976 { lat: 17, common_pid: 2303 } 2822 { lat: 17, common_pid: 2303 } hitcount: 1
2977 { lat: 18, common_pid: 2304 } 2823 { lat: 18, common_pid: 2304 } hitcount: 1
2978 { lat: 18, common_pid: 2302 } 2824 { lat: 18, common_pid: 2302 } hitcount: 8
2979 { lat: 18, common_pid: 2299 } 2825 { lat: 18, common_pid: 2299 } hitcount: 1
2980 { lat: 18, common_pid: 2301 } 2826 { lat: 18, common_pid: 2301 } hitcount: 1
2981 { lat: 19, common_pid: 2303 } 2827 { lat: 19, common_pid: 2303 } hitcount: 4
2982 { lat: 19, common_pid: 2304 } 2828 { lat: 19, common_pid: 2304 } hitcount: 5
2983 { lat: 19, common_pid: 2302 } 2829 { lat: 19, common_pid: 2302 } hitcount: 4
2984 { lat: 19, common_pid: 2299 } 2830 { lat: 19, common_pid: 2299 } hitcount: 3
2985 { lat: 19, common_pid: 2306 } 2831 { lat: 19, common_pid: 2306 } hitcount: 1
2986 { lat: 19, common_pid: 2300 } 2832 { lat: 19, common_pid: 2300 } hitcount: 4
2987 { lat: 19, common_pid: 2305 } 2833 { lat: 19, common_pid: 2305 } hitcount: 5
2988 { lat: 20, common_pid: 2299 } 2834 { lat: 20, common_pid: 2299 } hitcount: 2
2989 { lat: 20, common_pid: 2302 } 2835 { lat: 20, common_pid: 2302 } hitcount: 3
2990 { lat: 20, common_pid: 2305 } 2836 { lat: 20, common_pid: 2305 } hitcount: 1
2991 { lat: 20, common_pid: 2300 } 2837 { lat: 20, common_pid: 2300 } hitcount: 2
2992 { lat: 20, common_pid: 2301 } 2838 { lat: 20, common_pid: 2301 } hitcount: 2
2993 { lat: 20, common_pid: 2303 } 2839 { lat: 20, common_pid: 2303 } hitcount: 3
2994 { lat: 21, common_pid: 2305 } 2840 { lat: 21, common_pid: 2305 } hitcount: 1
2995 { lat: 21, common_pid: 2299 } 2841 { lat: 21, common_pid: 2299 } hitcount: 5
2996 { lat: 21, common_pid: 2303 } 2842 { lat: 21, common_pid: 2303 } hitcount: 4
2997 { lat: 21, common_pid: 2302 } 2843 { lat: 21, common_pid: 2302 } hitcount: 7
2998 { lat: 21, common_pid: 2300 } 2844 { lat: 21, common_pid: 2300 } hitcount: 1
2999 { lat: 21, common_pid: 2301 } 2845 { lat: 21, common_pid: 2301 } hitcount: 5
3000 { lat: 21, common_pid: 2304 } 2846 { lat: 21, common_pid: 2304 } hitcount: 2
3001 { lat: 22, common_pid: 2302 } 2847 { lat: 22, common_pid: 2302 } hitcount: 5
3002 { lat: 22, common_pid: 2303 } 2848 { lat: 22, common_pid: 2303 } hitcount: 1
3003 { lat: 22, common_pid: 2306 } 2849 { lat: 22, common_pid: 2306 } hitcount: 3
3004 { lat: 22, common_pid: 2301 } 2850 { lat: 22, common_pid: 2301 } hitcount: 2
3005 { lat: 22, common_pid: 2300 } 2851 { lat: 22, common_pid: 2300 } hitcount: 1
3006 { lat: 22, common_pid: 2299 } 2852 { lat: 22, common_pid: 2299 } hitcount: 1
3007 { lat: 22, common_pid: 2305 } 2853 { lat: 22, common_pid: 2305 } hitcount: 1
3008 { lat: 22, common_pid: 2304 } 2854 { lat: 22, common_pid: 2304 } hitcount: 1
3009 { lat: 23, common_pid: 2299 } 2855 { lat: 23, common_pid: 2299 } hitcount: 1
3010 { lat: 23, common_pid: 2306 } 2856 { lat: 23, common_pid: 2306 } hitcount: 2
3011 { lat: 23, common_pid: 2302 } 2857 { lat: 23, common_pid: 2302 } hitcount: 6
3012 { lat: 24, common_pid: 2302 } 2858 { lat: 24, common_pid: 2302 } hitcount: 3
3013 { lat: 24, common_pid: 2300 } 2859 { lat: 24, common_pid: 2300 } hitcount: 1
3014 { lat: 24, common_pid: 2306 } 2860 { lat: 24, common_pid: 2306 } hitcount: 2
3015 { lat: 24, common_pid: 2305 } 2861 { lat: 24, common_pid: 2305 } hitcount: 1
3016 { lat: 24, common_pid: 2299 } 2862 { lat: 24, common_pid: 2299 } hitcount: 1
3017 { lat: 25, common_pid: 2300 } 2863 { lat: 25, common_pid: 2300 } hitcount: 1
3018 { lat: 25, common_pid: 2302 } 2864 { lat: 25, common_pid: 2302 } hitcount: 4
3019 { lat: 26, common_pid: 2302 } 2865 { lat: 26, common_pid: 2302 } hitcount: 2
3020 { lat: 27, common_pid: 2305 } 2866 { lat: 27, common_pid: 2305 } hitcount: 1
3021 { lat: 27, common_pid: 2300 } 2867 { lat: 27, common_pid: 2300 } hitcount: 1
3022 { lat: 27, common_pid: 2302 } 2868 { lat: 27, common_pid: 2302 } hitcount: 3
3023 { lat: 28, common_pid: 2306 } 2869 { lat: 28, common_pid: 2306 } hitcount: 1
3024 { lat: 28, common_pid: 2302 } 2870 { lat: 28, common_pid: 2302 } hitcount: 4
3025 { lat: 29, common_pid: 2302 } 2871 { lat: 29, common_pid: 2302 } hitcount: 1
3026 { lat: 29, common_pid: 2300 } 2872 { lat: 29, common_pid: 2300 } hitcount: 2
3027 { lat: 29, common_pid: 2306 } 2873 { lat: 29, common_pid: 2306 } hitcount: 1
3028 { lat: 29, common_pid: 2304 } 2874 { lat: 29, common_pid: 2304 } hitcount: 1
3029 { lat: 30, common_pid: 2302 } 2875 { lat: 30, common_pid: 2302 } hitcount: 4
3030 { lat: 31, common_pid: 2302 } 2876 { lat: 31, common_pid: 2302 } hitcount: 6
3031 { lat: 32, common_pid: 2302 } 2877 { lat: 32, common_pid: 2302 } hitcount: 1
3032 { lat: 33, common_pid: 2299 } 2878 { lat: 33, common_pid: 2299 } hitcount: 1
3033 { lat: 33, common_pid: 2302 } 2879 { lat: 33, common_pid: 2302 } hitcount: 3
3034 { lat: 34, common_pid: 2302 } 2880 { lat: 34, common_pid: 2302 } hitcount: 2
3035 { lat: 35, common_pid: 2302 } 2881 { lat: 35, common_pid: 2302 } hitcount: 1
3036 { lat: 35, common_pid: 2304 } 2882 { lat: 35, common_pid: 2304 } hitcount: 1
3037 { lat: 36, common_pid: 2302 } 2883 { lat: 36, common_pid: 2302 } hitcount: 4
3038 { lat: 37, common_pid: 2302 } 2884 { lat: 37, common_pid: 2302 } hitcount: 6
3039 { lat: 38, common_pid: 2302 } 2885 { lat: 38, common_pid: 2302 } hitcount: 2
3040 { lat: 39, common_pid: 2302 } 2886 { lat: 39, common_pid: 2302 } hitcount: 2
3041 { lat: 39, common_pid: 2304 } 2887 { lat: 39, common_pid: 2304 } hitcount: 1
3042 { lat: 40, common_pid: 2304 } 2888 { lat: 40, common_pid: 2304 } hitcount: 2
3043 { lat: 40, common_pid: 2302 } 2889 { lat: 40, common_pid: 2302 } hitcount: 5
3044 { lat: 41, common_pid: 2304 } 2890 { lat: 41, common_pid: 2304 } hitcount: 1
3045 { lat: 41, common_pid: 2302 } 2891 { lat: 41, common_pid: 2302 } hitcount: 8
3046 { lat: 42, common_pid: 2302 } 2892 { lat: 42, common_pid: 2302 } hitcount: 6
3047 { lat: 42, common_pid: 2304 } 2893 { lat: 42, common_pid: 2304 } hitcount: 1
3048 { lat: 43, common_pid: 2302 } 2894 { lat: 43, common_pid: 2302 } hitcount: 3
3049 { lat: 43, common_pid: 2304 } 2895 { lat: 43, common_pid: 2304 } hitcount: 4
3050 { lat: 44, common_pid: 2302 } 2896 { lat: 44, common_pid: 2302 } hitcount: 6
3051 { lat: 45, common_pid: 2302 } 2897 { lat: 45, common_pid: 2302 } hitcount: 5
3052 { lat: 46, common_pid: 2302 } 2898 { lat: 46, common_pid: 2302 } hitcount: 5
3053 { lat: 47, common_pid: 2302 } 2899 { lat: 47, common_pid: 2302 } hitcount: 7
3054 { lat: 48, common_pid: 2301 } 2900 { lat: 48, common_pid: 2301 } hitcount: 1
3055 { lat: 48, common_pid: 2302 } 2901 { lat: 48, common_pid: 2302 } hitcount: 9
3056 { lat: 49, common_pid: 2302 } 2902 { lat: 49, common_pid: 2302 } hitcount: 3
3057 { lat: 50, common_pid: 2302 } 2903 { lat: 50, common_pid: 2302 } hitcount: 1
3058 { lat: 50, common_pid: 2301 } 2904 { lat: 50, common_pid: 2301 } hitcount: 1
3059 { lat: 51, common_pid: 2302 } 2905 { lat: 51, common_pid: 2302 } hitcount: 2
3060 { lat: 51, common_pid: 2301 } 2906 { lat: 51, common_pid: 2301 } hitcount: 1
3061 { lat: 61, common_pid: 2302 } 2907 { lat: 61, common_pid: 2302 } hitcount: 1
3062 { lat: 110, common_pid: 2302 } 2908 { lat: 110, common_pid: 2302 } hitcount: 1
3063 2909
3064 Totals: 2910 Totals:
3065 Hits: 89565 2911 Hits: 89565
3066 Entries: 158 2912 Entries: 158
3067 Dropped: 0 2913 Dropped: 0
3068 2914
3069 This doesn't tell us any information about ho 2915 This doesn't tell us any information about how late cyclictest may have
3070 woken up, but it does show us a nice histogra 2916 woken up, but it does show us a nice histogram of how long it took from
3071 the time that cyclictest was woken to the tim 2917 the time that cyclictest was woken to the time it made it into user space.
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