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