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