Loading...
1perf-stat(1)
2============
3
4NAME
5----
6perf-stat - Run a command and gather performance counter statistics
7
8SYNOPSIS
9--------
10[verse]
11'perf stat' [-e <EVENT> | --event=EVENT] [-a] <command>
12'perf stat' [-e <EVENT> | --event=EVENT] [-a] -- <command> [<options>]
13'perf stat' [-e <EVENT> | --event=EVENT] [-a] record [-o file] -- <command> [<options>]
14'perf stat' report [-i file]
15
16DESCRIPTION
17-----------
18This command runs a command and gathers performance counter statistics
19from it.
20
21
22OPTIONS
23-------
24<command>...::
25 Any command you can specify in a shell.
26
27record::
28 See STAT RECORD.
29
30report::
31 See STAT REPORT.
32
33-e::
34--event=::
35 Select the PMU event. Selection can be:
36
37 - a symbolic event name (use 'perf list' to list all events)
38
39 - a raw PMU event (eventsel+umask) in the form of rNNN where NNN is a
40 hexadecimal event descriptor.
41
42 - a symbolic or raw PMU event followed by an optional colon
43 and a list of event modifiers, e.g., cpu-cycles:p. See the
44 linkperf:perf-list[1] man page for details on event modifiers.
45
46 - a symbolically formed event like 'pmu/param1=0x3,param2/' where
47 param1 and param2 are defined as formats for the PMU in
48 /sys/bus/event_source/devices/<pmu>/format/*
49
50 'percore' is a event qualifier that sums up the event counts for both
51 hardware threads in a core. For example:
52 perf stat -A -a -e cpu/event,percore=1/,otherevent ...
53
54 - a symbolically formed event like 'pmu/config=M,config1=N,config2=K/'
55 where M, N, K are numbers (in decimal, hex, octal format).
56 Acceptable values for each of 'config', 'config1' and 'config2'
57 parameters are defined by corresponding entries in
58 /sys/bus/event_source/devices/<pmu>/format/*
59
60 Note that the last two syntaxes support prefix and glob matching in
61 the PMU name to simplify creation of events across multiple instances
62 of the same type of PMU in large systems (e.g. memory controller PMUs).
63 Multiple PMU instances are typical for uncore PMUs, so the prefix
64 'uncore_' is also ignored when performing this match.
65
66
67-i::
68--no-inherit::
69 child tasks do not inherit counters
70-p::
71--pid=<pid>::
72 stat events on existing process id (comma separated list)
73
74-t::
75--tid=<tid>::
76 stat events on existing thread id (comma separated list)
77
78-b::
79--bpf-prog::
80 stat events on existing bpf program id (comma separated list),
81 requiring root rights. bpftool-prog could be used to find program
82 id all bpf programs in the system. For example:
83
84 # bpftool prog | head -n 1
85 17247: tracepoint name sys_enter tag 192d548b9d754067 gpl
86
87 # perf stat -e cycles,instructions --bpf-prog 17247 --timeout 1000
88
89 Performance counter stats for 'BPF program(s) 17247':
90
91 85,967 cycles
92 28,982 instructions # 0.34 insn per cycle
93
94 1.102235068 seconds time elapsed
95
96--bpf-counters::
97 Use BPF programs to aggregate readings from perf_events. This
98 allows multiple perf-stat sessions that are counting the same metric (cycles,
99 instructions, etc.) to share hardware counters.
100 To use BPF programs on common events by default, use
101 "perf config stat.bpf-counter-events=<list_of_events>".
102
103--bpf-attr-map::
104 With option "--bpf-counters", different perf-stat sessions share
105 information about shared BPF programs and maps via a pinned hashmap.
106 Use "--bpf-attr-map" to specify the path of this pinned hashmap.
107 The default path is /sys/fs/bpf/perf_attr_map.
108
109ifdef::HAVE_LIBPFM[]
110--pfm-events events::
111Select a PMU event using libpfm4 syntax (see http://perfmon2.sf.net)
112including support for event filters. For example '--pfm-events
113inst_retired:any_p:u:c=1:i'. More than one event can be passed to the
114option using the comma separator. Hardware events and generic hardware
115events cannot be mixed together. The latter must be used with the -e
116option. The -e option and this one can be mixed and matched. Events
117can be grouped using the {} notation.
118endif::HAVE_LIBPFM[]
119
120-a::
121--all-cpus::
122 system-wide collection from all CPUs (default if no target is specified)
123
124--no-scale::
125 Don't scale/normalize counter values
126
127-d::
128--detailed::
129 print more detailed statistics, can be specified up to 3 times
130
131 -d: detailed events, L1 and LLC data cache
132 -d -d: more detailed events, dTLB and iTLB events
133 -d -d -d: very detailed events, adding prefetch events
134
135-r::
136--repeat=<n>::
137 repeat command and print average + stddev (max: 100). 0 means forever.
138
139-B::
140--big-num::
141 print large numbers with thousands' separators according to locale.
142 Enabled by default. Use "--no-big-num" to disable.
143 Default setting can be changed with "perf config stat.big-num=false".
144
145-C::
146--cpu=::
147Count only on the list of CPUs provided. Multiple CPUs can be provided as a
148comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2.
149In per-thread mode, this option is ignored. The -a option is still necessary
150to activate system-wide monitoring. Default is to count on all CPUs.
151
152-A::
153--no-aggr::
154Do not aggregate counts across all monitored CPUs.
155
156-n::
157--null::
158null run - Don't start any counters.
159
160This can be useful to measure just elapsed wall-clock time - or to assess the
161raw overhead of perf stat itself, without running any counters.
162
163-v::
164--verbose::
165 be more verbose (show counter open errors, etc)
166
167-x SEP::
168--field-separator SEP::
169print counts using a CSV-style output to make it easy to import directly into
170spreadsheets. Columns are separated by the string specified in SEP.
171
172--table:: Display time for each run (-r option), in a table format, e.g.:
173
174 $ perf stat --null -r 5 --table perf bench sched pipe
175
176 Performance counter stats for 'perf bench sched pipe' (5 runs):
177
178 # Table of individual measurements:
179 5.189 (-0.293) #
180 5.189 (-0.294) #
181 5.186 (-0.296) #
182 5.663 (+0.181) ##
183 6.186 (+0.703) ####
184
185 # Final result:
186 5.483 +- 0.198 seconds time elapsed ( +- 3.62% )
187
188-G name::
189--cgroup name::
190monitor only in the container (cgroup) called "name". This option is available only
191in per-cpu mode. The cgroup filesystem must be mounted. All threads belonging to
192container "name" are monitored when they run on the monitored CPUs. Multiple cgroups
193can be provided. Each cgroup is applied to the corresponding event, i.e., first cgroup
194to first event, second cgroup to second event and so on. It is possible to provide
195an empty cgroup (monitor all the time) using, e.g., -G foo,,bar. Cgroups must have
196corresponding events, i.e., they always refer to events defined earlier on the command
197line. If the user wants to track multiple events for a specific cgroup, the user can
198use '-e e1 -e e2 -G foo,foo' or just use '-e e1 -e e2 -G foo'.
199
200If wanting to monitor, say, 'cycles' for a cgroup and also for system wide, this
201command line can be used: 'perf stat -e cycles -G cgroup_name -a -e cycles'.
202
203--for-each-cgroup name::
204Expand event list for each cgroup in "name" (allow multiple cgroups separated
205by comma). It also support regex patterns to match multiple groups. This has same
206effect that repeating -e option and -G option for each event x name. This option
207cannot be used with -G/--cgroup option.
208
209-o file::
210--output file::
211Print the output into the designated file.
212
213--append::
214Append to the output file designated with the -o option. Ignored if -o is not specified.
215
216--log-fd::
217
218Log output to fd, instead of stderr. Complementary to --output, and mutually exclusive
219with it. --append may be used here. Examples:
220 3>results perf stat --log-fd 3 -- $cmd
221 3>>results perf stat --log-fd 3 --append -- $cmd
222
223--control=fifo:ctl-fifo[,ack-fifo]::
224--control=fd:ctl-fd[,ack-fd]::
225ctl-fifo / ack-fifo are opened and used as ctl-fd / ack-fd as follows.
226Listen on ctl-fd descriptor for command to control measurement ('enable': enable events,
227'disable': disable events). Measurements can be started with events disabled using
228--delay=-1 option. Optionally send control command completion ('ack\n') to ack-fd descriptor
229to synchronize with the controlling process. Example of bash shell script to enable and
230disable events during measurements:
231
232 #!/bin/bash
233
234 ctl_dir=/tmp/
235
236 ctl_fifo=${ctl_dir}perf_ctl.fifo
237 test -p ${ctl_fifo} && unlink ${ctl_fifo}
238 mkfifo ${ctl_fifo}
239 exec {ctl_fd}<>${ctl_fifo}
240
241 ctl_ack_fifo=${ctl_dir}perf_ctl_ack.fifo
242 test -p ${ctl_ack_fifo} && unlink ${ctl_ack_fifo}
243 mkfifo ${ctl_ack_fifo}
244 exec {ctl_fd_ack}<>${ctl_ack_fifo}
245
246 perf stat -D -1 -e cpu-cycles -a -I 1000 \
247 --control fd:${ctl_fd},${ctl_fd_ack} \
248 -- sleep 30 &
249 perf_pid=$!
250
251 sleep 5 && echo 'enable' >&${ctl_fd} && read -u ${ctl_fd_ack} e1 && echo "enabled(${e1})"
252 sleep 10 && echo 'disable' >&${ctl_fd} && read -u ${ctl_fd_ack} d1 && echo "disabled(${d1})"
253
254 exec {ctl_fd_ack}>&-
255 unlink ${ctl_ack_fifo}
256
257 exec {ctl_fd}>&-
258 unlink ${ctl_fifo}
259
260 wait -n ${perf_pid}
261 exit $?
262
263
264--pre::
265--post::
266 Pre and post measurement hooks, e.g.:
267
268perf stat --repeat 10 --null --sync --pre 'make -s O=defconfig-build/clean' -- make -s -j64 O=defconfig-build/ bzImage
269
270-I msecs::
271--interval-print msecs::
272Print count deltas every N milliseconds (minimum: 1ms)
273The overhead percentage could be high in some cases, for instance with small, sub 100ms intervals. Use with caution.
274 example: 'perf stat -I 1000 -e cycles -a sleep 5'
275
276If the metric exists, it is calculated by the counts generated in this interval and the metric is printed after #.
277
278--interval-count times::
279Print count deltas for fixed number of times.
280This option should be used together with "-I" option.
281 example: 'perf stat -I 1000 --interval-count 2 -e cycles -a'
282
283--interval-clear::
284Clear the screen before next interval.
285
286--timeout msecs::
287Stop the 'perf stat' session and print count deltas after N milliseconds (minimum: 10 ms).
288This option is not supported with the "-I" option.
289 example: 'perf stat --time 2000 -e cycles -a'
290
291--metric-only::
292Only print computed metrics. Print them in a single line.
293Don't show any raw values. Not supported with --per-thread.
294
295--per-socket::
296Aggregate counts per processor socket for system-wide mode measurements. This
297is a useful mode to detect imbalance between sockets. To enable this mode,
298use --per-socket in addition to -a. (system-wide). The output includes the
299socket number and the number of online processors on that socket. This is
300useful to gauge the amount of aggregation.
301
302--per-die::
303Aggregate counts per processor die for system-wide mode measurements. This
304is a useful mode to detect imbalance between dies. To enable this mode,
305use --per-die in addition to -a. (system-wide). The output includes the
306die number and the number of online processors on that die. This is
307useful to gauge the amount of aggregation.
308
309--per-core::
310Aggregate counts per physical processor for system-wide mode measurements. This
311is a useful mode to detect imbalance between physical cores. To enable this mode,
312use --per-core in addition to -a. (system-wide). The output includes the
313core number and the number of online logical processors on that physical processor.
314
315--per-thread::
316Aggregate counts per monitored threads, when monitoring threads (-t option)
317or processes (-p option).
318
319--per-node::
320Aggregate counts per NUMA nodes for system-wide mode measurements. This
321is a useful mode to detect imbalance between NUMA nodes. To enable this
322mode, use --per-node in addition to -a. (system-wide).
323
324-D msecs::
325--delay msecs::
326After starting the program, wait msecs before measuring (-1: start with events
327disabled). This is useful to filter out the startup phase of the program,
328which is often very different.
329
330-T::
331--transaction::
332
333Print statistics of transactional execution if supported.
334
335--metric-no-group::
336By default, events to compute a metric are placed in weak groups. The
337group tries to enforce scheduling all or none of the events. The
338--metric-no-group option places events outside of groups and may
339increase the chance of the event being scheduled - leading to more
340accuracy. However, as events may not be scheduled together accuracy
341for metrics like instructions per cycle can be lower - as both metrics
342may no longer be being measured at the same time.
343
344--metric-no-merge::
345By default metric events in different weak groups can be shared if one
346group contains all the events needed by another. In such cases one
347group will be eliminated reducing event multiplexing and making it so
348that certain groups of metrics sum to 100%. A downside to sharing a
349group is that the group may require multiplexing and so accuracy for a
350small group that need not have multiplexing is lowered. This option
351forbids the event merging logic from sharing events between groups and
352may be used to increase accuracy in this case.
353
354--quiet::
355Don't print output. This is useful with perf stat record below to only
356write data to the perf.data file.
357
358STAT RECORD
359-----------
360Stores stat data into perf data file.
361
362-o file::
363--output file::
364Output file name.
365
366STAT REPORT
367-----------
368Reads and reports stat data from perf data file.
369
370-i file::
371--input file::
372Input file name.
373
374--per-socket::
375Aggregate counts per processor socket for system-wide mode measurements.
376
377--per-die::
378Aggregate counts per processor die for system-wide mode measurements.
379
380--per-core::
381Aggregate counts per physical processor for system-wide mode measurements.
382
383-M::
384--metrics::
385Print metrics or metricgroups specified in a comma separated list.
386For a group all metrics from the group are added.
387The events from the metrics are automatically measured.
388See perf list output for the possble metrics and metricgroups.
389
390-A::
391--no-aggr::
392Do not aggregate counts across all monitored CPUs.
393
394--topdown::
395Print complete top-down metrics supported by the CPU. This allows to
396determine bottle necks in the CPU pipeline for CPU bound workloads,
397by breaking the cycles consumed down into frontend bound, backend bound,
398bad speculation and retiring.
399
400Frontend bound means that the CPU cannot fetch and decode instructions fast
401enough. Backend bound means that computation or memory access is the bottle
402neck. Bad Speculation means that the CPU wasted cycles due to branch
403mispredictions and similar issues. Retiring means that the CPU computed without
404an apparently bottleneck. The bottleneck is only the real bottleneck
405if the workload is actually bound by the CPU and not by something else.
406
407For best results it is usually a good idea to use it with interval
408mode like -I 1000, as the bottleneck of workloads can change often.
409
410This enables --metric-only, unless overridden with --no-metric-only.
411
412The following restrictions only apply to older Intel CPUs and Atom,
413on newer CPUs (IceLake and later) TopDown can be collected for any thread:
414
415The top down metrics are collected per core instead of per
416CPU thread. Per core mode is automatically enabled
417and -a (global monitoring) is needed, requiring root rights or
418perf.perf_event_paranoid=-1.
419
420Topdown uses the full Performance Monitoring Unit, and needs
421disabling of the NMI watchdog (as root):
422echo 0 > /proc/sys/kernel/nmi_watchdog
423for best results. Otherwise the bottlenecks may be inconsistent
424on workload with changing phases.
425
426To interpret the results it is usually needed to know on which
427CPUs the workload runs on. If needed the CPUs can be forced using
428taskset.
429
430--td-level::
431Print the top-down statistics that equal to or lower than the input level.
432It allows users to print the interested top-down metrics level instead of
433the complete top-down metrics.
434
435The availability of the top-down metrics level depends on the hardware. For
436example, Ice Lake only supports L1 top-down metrics. The Sapphire Rapids
437supports both L1 and L2 top-down metrics.
438
439Default: 0 means the max level that the current hardware support.
440Error out if the input is higher than the supported max level.
441
442--no-merge::
443Do not merge results from same PMUs.
444
445When multiple events are created from a single event specification,
446stat will, by default, aggregate the event counts and show the result
447in a single row. This option disables that behavior and shows
448the individual events and counts.
449
450Multiple events are created from a single event specification when:
4511. Prefix or glob matching is used for the PMU name.
4522. Aliases, which are listed immediately after the Kernel PMU events
453 by perf list, are used.
454
455--smi-cost::
456Measure SMI cost if msr/aperf/ and msr/smi/ events are supported.
457
458During the measurement, the /sys/device/cpu/freeze_on_smi will be set to
459freeze core counters on SMI.
460The aperf counter will not be effected by the setting.
461The cost of SMI can be measured by (aperf - unhalted core cycles).
462
463In practice, the percentages of SMI cycles is very useful for performance
464oriented analysis. --metric_only will be applied by default.
465The output is SMI cycles%, equals to (aperf - unhalted core cycles) / aperf
466
467Users who wants to get the actual value can apply --no-metric-only.
468
469--all-kernel::
470Configure all used events to run in kernel space.
471
472--all-user::
473Configure all used events to run in user space.
474
475--percore-show-thread::
476The event modifier "percore" has supported to sum up the event counts
477for all hardware threads in a core and show the counts per core.
478
479This option with event modifier "percore" enabled also sums up the event
480counts for all hardware threads in a core but show the sum counts per
481hardware thread. This is essentially a replacement for the any bit and
482convenient for post processing.
483
484--summary::
485Print summary for interval mode (-I).
486
487--no-csv-summary::
488Don't print 'summary' at the first column for CVS summary output.
489This option must be used with -x and --summary.
490
491This option can be enabled in perf config by setting the variable
492'stat.no-csv-summary'.
493
494$ perf config stat.no-csv-summary=true
495
496EXAMPLES
497--------
498
499$ perf stat -- make
500
501 Performance counter stats for 'make':
502
503 83723.452481 task-clock:u (msec) # 1.004 CPUs utilized
504 0 context-switches:u # 0.000 K/sec
505 0 cpu-migrations:u # 0.000 K/sec
506 3,228,188 page-faults:u # 0.039 M/sec
507 229,570,665,834 cycles:u # 2.742 GHz
508 313,163,853,778 instructions:u # 1.36 insn per cycle
509 69,704,684,856 branches:u # 832.559 M/sec
510 2,078,861,393 branch-misses:u # 2.98% of all branches
511
512 83.409183620 seconds time elapsed
513
514 74.684747000 seconds user
515 8.739217000 seconds sys
516
517TIMINGS
518-------
519As displayed in the example above we can display 3 types of timings.
520We always display the time the counters were enabled/alive:
521
522 83.409183620 seconds time elapsed
523
524For workload sessions we also display time the workloads spent in
525user/system lands:
526
527 74.684747000 seconds user
528 8.739217000 seconds sys
529
530Those times are the very same as displayed by the 'time' tool.
531
532CSV FORMAT
533----------
534
535With -x, perf stat is able to output a not-quite-CSV format output
536Commas in the output are not put into "". To make it easy to parse
537it is recommended to use a different character like -x \;
538
539The fields are in this order:
540
541 - optional usec time stamp in fractions of second (with -I xxx)
542 - optional CPU, core, or socket identifier
543 - optional number of logical CPUs aggregated
544 - counter value
545 - unit of the counter value or empty
546 - event name
547 - run time of counter
548 - percentage of measurement time the counter was running
549 - optional variance if multiple values are collected with -r
550 - optional metric value
551 - optional unit of metric
552
553Additional metrics may be printed with all earlier fields being empty.
554
555include::intel-hybrid.txt[]
556
557SEE ALSO
558--------
559linkperf:perf-top[1], linkperf:perf-list[1]
1perf-stat(1)
2============
3
4NAME
5----
6perf-stat - Run a command and gather performance counter statistics
7
8SYNOPSIS
9--------
10[verse]
11'perf stat' [-e <EVENT> | --event=EVENT] [-a] <command>
12'perf stat' [-e <EVENT> | --event=EVENT] [-a] \-- <command> [<options>]
13'perf stat' [-e <EVENT> | --event=EVENT] [-a] record [-o file] \-- <command> [<options>]
14'perf stat' report [-i file]
15
16DESCRIPTION
17-----------
18This command runs a command and gathers performance counter statistics
19from it.
20
21
22OPTIONS
23-------
24<command>...::
25 Any command you can specify in a shell.
26
27record::
28 See STAT RECORD.
29
30report::
31 See STAT REPORT.
32
33-e::
34--event=::
35 Select the PMU event. Selection can be:
36
37 - a symbolic event name (use 'perf list' to list all events)
38
39 - a raw PMU event in the form of rN where N is a hexadecimal value
40 that represents the raw register encoding with the layout of the
41 event control registers as described by entries in
42 /sys/bus/event_source/devices/cpu/format/*.
43
44 - a symbolic or raw PMU event followed by an optional colon
45 and a list of event modifiers, e.g., cpu-cycles:p. See the
46 linkperf:perf-list[1] man page for details on event modifiers.
47
48 - a symbolically formed event like 'pmu/param1=0x3,param2/' where
49 param1 and param2 are defined as formats for the PMU in
50 /sys/bus/event_source/devices/<pmu>/format/*
51
52 'percore' is a event qualifier that sums up the event counts for both
53 hardware threads in a core. For example:
54 perf stat -A -a -e cpu/event,percore=1/,otherevent ...
55
56 - a symbolically formed event like 'pmu/config=M,config1=N,config2=K/'
57 where M, N, K are numbers (in decimal, hex, octal format).
58 Acceptable values for each of 'config', 'config1' and 'config2'
59 parameters are defined by corresponding entries in
60 /sys/bus/event_source/devices/<pmu>/format/*
61
62 Note that the last two syntaxes support prefix and glob matching in
63 the PMU name to simplify creation of events across multiple instances
64 of the same type of PMU in large systems (e.g. memory controller PMUs).
65 Multiple PMU instances are typical for uncore PMUs, so the prefix
66 'uncore_' is also ignored when performing this match.
67
68
69-i::
70--no-inherit::
71 child tasks do not inherit counters
72-p::
73--pid=<pid>::
74 stat events on existing process id (comma separated list)
75
76-t::
77--tid=<tid>::
78 stat events on existing thread id (comma separated list)
79
80-b::
81--bpf-prog::
82 stat events on existing bpf program id (comma separated list),
83 requiring root rights. bpftool-prog could be used to find program
84 id all bpf programs in the system. For example:
85
86 # bpftool prog | head -n 1
87 17247: tracepoint name sys_enter tag 192d548b9d754067 gpl
88
89 # perf stat -e cycles,instructions --bpf-prog 17247 --timeout 1000
90
91 Performance counter stats for 'BPF program(s) 17247':
92
93 85,967 cycles
94 28,982 instructions # 0.34 insn per cycle
95
96 1.102235068 seconds time elapsed
97
98--bpf-counters::
99 Use BPF programs to aggregate readings from perf_events. This
100 allows multiple perf-stat sessions that are counting the same metric (cycles,
101 instructions, etc.) to share hardware counters.
102 To use BPF programs on common events by default, use
103 "perf config stat.bpf-counter-events=<list_of_events>".
104
105--bpf-attr-map::
106 With option "--bpf-counters", different perf-stat sessions share
107 information about shared BPF programs and maps via a pinned hashmap.
108 Use "--bpf-attr-map" to specify the path of this pinned hashmap.
109 The default path is /sys/fs/bpf/perf_attr_map.
110
111ifdef::HAVE_LIBPFM[]
112--pfm-events events::
113Select a PMU event using libpfm4 syntax (see http://perfmon2.sf.net)
114including support for event filters. For example '--pfm-events
115inst_retired:any_p:u:c=1:i'. More than one event can be passed to the
116option using the comma separator. Hardware events and generic hardware
117events cannot be mixed together. The latter must be used with the -e
118option. The -e option and this one can be mixed and matched. Events
119can be grouped using the {} notation.
120endif::HAVE_LIBPFM[]
121
122-a::
123--all-cpus::
124 system-wide collection from all CPUs (default if no target is specified)
125
126--no-scale::
127 Don't scale/normalize counter values
128
129-d::
130--detailed::
131 print more detailed statistics, can be specified up to 3 times
132
133 -d: detailed events, L1 and LLC data cache
134 -d -d: more detailed events, dTLB and iTLB events
135 -d -d -d: very detailed events, adding prefetch events
136
137-r::
138--repeat=<n>::
139 repeat command and print average + stddev (max: 100). 0 means forever.
140
141-B::
142--big-num::
143 print large numbers with thousands' separators according to locale.
144 Enabled by default. Use "--no-big-num" to disable.
145 Default setting can be changed with "perf config stat.big-num=false".
146
147-C::
148--cpu=::
149Count only on the list of CPUs provided. Multiple CPUs can be provided as a
150comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2.
151In per-thread mode, this option is ignored. The -a option is still necessary
152to activate system-wide monitoring. Default is to count on all CPUs.
153
154-A::
155--no-aggr::
156Do not aggregate counts across all monitored CPUs.
157
158-n::
159--null::
160null run - Don't start any counters.
161
162This can be useful to measure just elapsed wall-clock time - or to assess the
163raw overhead of perf stat itself, without running any counters.
164
165-v::
166--verbose::
167 be more verbose (show counter open errors, etc)
168
169-x SEP::
170--field-separator SEP::
171print counts using a CSV-style output to make it easy to import directly into
172spreadsheets. Columns are separated by the string specified in SEP.
173
174--table:: Display time for each run (-r option), in a table format, e.g.:
175
176 $ perf stat --null -r 5 --table perf bench sched pipe
177
178 Performance counter stats for 'perf bench sched pipe' (5 runs):
179
180 # Table of individual measurements:
181 5.189 (-0.293) #
182 5.189 (-0.294) #
183 5.186 (-0.296) #
184 5.663 (+0.181) ##
185 6.186 (+0.703) ####
186
187 # Final result:
188 5.483 +- 0.198 seconds time elapsed ( +- 3.62% )
189
190-G name::
191--cgroup name::
192monitor only in the container (cgroup) called "name". This option is available only
193in per-cpu mode. The cgroup filesystem must be mounted. All threads belonging to
194container "name" are monitored when they run on the monitored CPUs. Multiple cgroups
195can be provided. Each cgroup is applied to the corresponding event, i.e., first cgroup
196to first event, second cgroup to second event and so on. It is possible to provide
197an empty cgroup (monitor all the time) using, e.g., -G foo,,bar. Cgroups must have
198corresponding events, i.e., they always refer to events defined earlier on the command
199line. If the user wants to track multiple events for a specific cgroup, the user can
200use '-e e1 -e e2 -G foo,foo' or just use '-e e1 -e e2 -G foo'.
201
202If wanting to monitor, say, 'cycles' for a cgroup and also for system wide, this
203command line can be used: 'perf stat -e cycles -G cgroup_name -a -e cycles'.
204
205--for-each-cgroup name::
206Expand event list for each cgroup in "name" (allow multiple cgroups separated
207by comma). It also support regex patterns to match multiple groups. This has same
208effect that repeating -e option and -G option for each event x name. This option
209cannot be used with -G/--cgroup option.
210
211-o file::
212--output file::
213Print the output into the designated file.
214
215--append::
216Append to the output file designated with the -o option. Ignored if -o is not specified.
217
218--log-fd::
219
220Log output to fd, instead of stderr. Complementary to --output, and mutually exclusive
221with it. --append may be used here. Examples:
222 3>results perf stat --log-fd 3 \-- $cmd
223 3>>results perf stat --log-fd 3 --append \-- $cmd
224
225--control=fifo:ctl-fifo[,ack-fifo]::
226--control=fd:ctl-fd[,ack-fd]::
227ctl-fifo / ack-fifo are opened and used as ctl-fd / ack-fd as follows.
228Listen on ctl-fd descriptor for command to control measurement ('enable': enable events,
229'disable': disable events). Measurements can be started with events disabled using
230--delay=-1 option. Optionally send control command completion ('ack\n') to ack-fd descriptor
231to synchronize with the controlling process. Example of bash shell script to enable and
232disable events during measurements:
233
234 #!/bin/bash
235
236 ctl_dir=/tmp/
237
238 ctl_fifo=${ctl_dir}perf_ctl.fifo
239 test -p ${ctl_fifo} && unlink ${ctl_fifo}
240 mkfifo ${ctl_fifo}
241 exec {ctl_fd}<>${ctl_fifo}
242
243 ctl_ack_fifo=${ctl_dir}perf_ctl_ack.fifo
244 test -p ${ctl_ack_fifo} && unlink ${ctl_ack_fifo}
245 mkfifo ${ctl_ack_fifo}
246 exec {ctl_fd_ack}<>${ctl_ack_fifo}
247
248 perf stat -D -1 -e cpu-cycles -a -I 1000 \
249 --control fd:${ctl_fd},${ctl_fd_ack} \
250 \-- sleep 30 &
251 perf_pid=$!
252
253 sleep 5 && echo 'enable' >&${ctl_fd} && read -u ${ctl_fd_ack} e1 && echo "enabled(${e1})"
254 sleep 10 && echo 'disable' >&${ctl_fd} && read -u ${ctl_fd_ack} d1 && echo "disabled(${d1})"
255
256 exec {ctl_fd_ack}>&-
257 unlink ${ctl_ack_fifo}
258
259 exec {ctl_fd}>&-
260 unlink ${ctl_fifo}
261
262 wait -n ${perf_pid}
263 exit $?
264
265
266--pre::
267--post::
268 Pre and post measurement hooks, e.g.:
269
270perf stat --repeat 10 --null --sync --pre 'make -s O=defconfig-build/clean' \-- make -s -j64 O=defconfig-build/ bzImage
271
272-I msecs::
273--interval-print msecs::
274Print count deltas every N milliseconds (minimum: 1ms)
275The overhead percentage could be high in some cases, for instance with small, sub 100ms intervals. Use with caution.
276 example: 'perf stat -I 1000 -e cycles -a sleep 5'
277
278If the metric exists, it is calculated by the counts generated in this interval and the metric is printed after #.
279
280--interval-count times::
281Print count deltas for fixed number of times.
282This option should be used together with "-I" option.
283 example: 'perf stat -I 1000 --interval-count 2 -e cycles -a'
284
285--interval-clear::
286Clear the screen before next interval.
287
288--timeout msecs::
289Stop the 'perf stat' session and print count deltas after N milliseconds (minimum: 10 ms).
290This option is not supported with the "-I" option.
291 example: 'perf stat --time 2000 -e cycles -a'
292
293--metric-only::
294Only print computed metrics. Print them in a single line.
295Don't show any raw values. Not supported with --per-thread.
296
297--per-socket::
298Aggregate counts per processor socket for system-wide mode measurements. This
299is a useful mode to detect imbalance between sockets. To enable this mode,
300use --per-socket in addition to -a. (system-wide). The output includes the
301socket number and the number of online processors on that socket. This is
302useful to gauge the amount of aggregation.
303
304--per-die::
305Aggregate counts per processor die for system-wide mode measurements. This
306is a useful mode to detect imbalance between dies. To enable this mode,
307use --per-die in addition to -a. (system-wide). The output includes the
308die number and the number of online processors on that die. This is
309useful to gauge the amount of aggregation.
310
311--per-cluster::
312Aggregate counts per processor cluster for system-wide mode measurement. This
313is a useful mode to detect imbalance between clusters. To enable this mode,
314use --per-cluster in addition to -a. (system-wide). The output includes the
315cluster number and the number of online processors on that cluster. This is
316useful to gauge the amount of aggregation. The information of cluster ID and
317related CPUs can be gotten from /sys/devices/system/cpu/cpuX/topology/cluster_{id, cpus}.
318
319--per-cache::
320Aggregate counts per cache instance for system-wide mode measurements. By
321default, the aggregation happens for the cache level at the highest index
322in the system. To specify a particular level, mention the cache level
323alongside the option in the format [Ll][1-9][0-9]*. For example:
324Using option "--per-cache=l3" or "--per-cache=L3" will aggregate the
325information at the boundary of the level 3 cache in the system.
326
327--per-core::
328Aggregate counts per physical processor for system-wide mode measurements. This
329is a useful mode to detect imbalance between physical cores. To enable this mode,
330use --per-core in addition to -a. (system-wide). The output includes the
331core number and the number of online logical processors on that physical processor.
332
333--per-thread::
334Aggregate counts per monitored threads, when monitoring threads (-t option)
335or processes (-p option).
336
337--per-node::
338Aggregate counts per NUMA nodes for system-wide mode measurements. This
339is a useful mode to detect imbalance between NUMA nodes. To enable this
340mode, use --per-node in addition to -a. (system-wide).
341
342-D msecs::
343--delay msecs::
344After starting the program, wait msecs before measuring (-1: start with events
345disabled). This is useful to filter out the startup phase of the program,
346which is often very different.
347
348-T::
349--transaction::
350
351Print statistics of transactional execution if supported.
352
353--metric-no-group::
354By default, events to compute a metric are placed in weak groups. The
355group tries to enforce scheduling all or none of the events. The
356--metric-no-group option places events outside of groups and may
357increase the chance of the event being scheduled - leading to more
358accuracy. However, as events may not be scheduled together accuracy
359for metrics like instructions per cycle can be lower - as both metrics
360may no longer be being measured at the same time.
361
362--metric-no-merge::
363By default metric events in different weak groups can be shared if one
364group contains all the events needed by another. In such cases one
365group will be eliminated reducing event multiplexing and making it so
366that certain groups of metrics sum to 100%. A downside to sharing a
367group is that the group may require multiplexing and so accuracy for a
368small group that need not have multiplexing is lowered. This option
369forbids the event merging logic from sharing events between groups and
370may be used to increase accuracy in this case.
371
372--metric-no-threshold::
373Metric thresholds may increase the number of events necessary to
374compute whether a metric has exceeded its threshold expression. This
375may not be desirable, for example, as the events can introduce
376multiplexing. This option disables the adding of threshold expression
377events for a metric. However, if there are sufficient events to
378compute the threshold then the threshold is still computed and used to
379color the metric's computed value.
380
381--quiet::
382Don't print output, warnings or messages. This is useful with perf stat
383record below to only write data to the perf.data file.
384
385STAT RECORD
386-----------
387Stores stat data into perf data file.
388
389-o file::
390--output file::
391Output file name.
392
393STAT REPORT
394-----------
395Reads and reports stat data from perf data file.
396
397-i file::
398--input file::
399Input file name.
400
401--per-socket::
402Aggregate counts per processor socket for system-wide mode measurements.
403
404--per-die::
405Aggregate counts per processor die for system-wide mode measurements.
406
407--per-cluster::
408Aggregate counts perf processor cluster for system-wide mode measurements.
409
410--per-cache::
411Aggregate counts per cache instance for system-wide mode measurements. By
412default, the aggregation happens for the cache level at the highest index
413in the system. To specify a particular level, mention the cache level
414alongside the option in the format [Ll][1-9][0-9]*. For example: Using
415option "--per-cache=l3" or "--per-cache=L3" will aggregate the
416information at the boundary of the level 3 cache in the system.
417
418--per-core::
419Aggregate counts per physical processor for system-wide mode measurements.
420
421-M::
422--metrics::
423Print metrics or metricgroups specified in a comma separated list.
424For a group all metrics from the group are added.
425The events from the metrics are automatically measured.
426See perf list output for the possible metrics and metricgroups.
427
428 When threshold information is available for a metric, the
429 color red is used to signify a metric has exceeded a threshold
430 while green shows it hasn't. The default color means that
431 no threshold information was available or the threshold
432 couldn't be computed.
433
434-A::
435--no-aggr::
436--no-merge::
437Do not aggregate/merge counts across monitored CPUs or PMUs.
438
439When multiple events are created from a single event specification,
440stat will, by default, aggregate the event counts and show the result
441in a single row. This option disables that behavior and shows the
442individual events and counts.
443
444Multiple events are created from a single event specification when:
445
4461. PID monitoring isn't requested and the system has more than one
447 CPU. For example, a system with 8 SMT threads will have one event
448 opened on each thread and aggregation is performed across them.
449
4502. Prefix or glob wildcard matching is used for the PMU name. For
451 example, multiple memory controller PMUs may exist typically with a
452 suffix of _0, _1, etc. By default the event counts will all be
453 combined if the PMU is specified without the suffix such as
454 uncore_imc rather than uncore_imc_0.
455
4563. Aliases, which are listed immediately after the Kernel PMU events
457 by perf list, are used.
458
459--hybrid-merge::
460Merge core event counts from all core PMUs. In hybrid or big.LITTLE
461systems by default each core PMU will report its count
462separately. This option forces core PMU counts to be combined to give
463a behavior closer to having a single CPU type in the system.
464
465--topdown::
466Print top-down metrics supported by the CPU. This allows to determine
467bottle necks in the CPU pipeline for CPU bound workloads, by breaking
468the cycles consumed down into frontend bound, backend bound, bad
469speculation and retiring.
470
471Frontend bound means that the CPU cannot fetch and decode instructions fast
472enough. Backend bound means that computation or memory access is the bottle
473neck. Bad Speculation means that the CPU wasted cycles due to branch
474mispredictions and similar issues. Retiring means that the CPU computed without
475an apparently bottleneck. The bottleneck is only the real bottleneck
476if the workload is actually bound by the CPU and not by something else.
477
478For best results it is usually a good idea to use it with interval
479mode like -I 1000, as the bottleneck of workloads can change often.
480
481This enables --metric-only, unless overridden with --no-metric-only.
482
483The following restrictions only apply to older Intel CPUs and Atom,
484on newer CPUs (IceLake and later) TopDown can be collected for any thread:
485
486The top down metrics are collected per core instead of per
487CPU thread. Per core mode is automatically enabled
488and -a (global monitoring) is needed, requiring root rights or
489perf.perf_event_paranoid=-1.
490
491Topdown uses the full Performance Monitoring Unit, and needs
492disabling of the NMI watchdog (as root):
493echo 0 > /proc/sys/kernel/nmi_watchdog
494for best results. Otherwise the bottlenecks may be inconsistent
495on workload with changing phases.
496
497To interpret the results it is usually needed to know on which
498CPUs the workload runs on. If needed the CPUs can be forced using
499taskset.
500
501--record-tpebs::
502Enable automatic sampling on Intel TPEBS retire_latency events (event with :R
503modifier). Without this option, perf would not capture dynamic retire_latency
504at runtime. Currently, a zero value is assigned to the retire_latency event when
505this option is not set. The TPEBS hardware feature starts from Intel Granite
506Rapids microarchitecture. This option only exists in X86_64 and is meaningful on
507Intel platforms with TPEBS feature.
508
509--td-level::
510Print the top-down statistics that equal the input level. It allows
511users to print the interested top-down metrics level instead of the
512level 1 top-down metrics.
513
514As the higher levels gather more metrics and use more counters they
515will be less accurate. By convention a metric can be examined by
516appending '_group' to it and this will increase accuracy compared to
517gathering all metrics for a level. For example, level 1 analysis may
518highlight 'tma_frontend_bound'. This metric may be drilled into with
519'tma_frontend_bound_group' with
520'perf stat -M tma_frontend_bound_group...'.
521
522Error out if the input is higher than the supported max level.
523
524--smi-cost::
525Measure SMI cost if msr/aperf/ and msr/smi/ events are supported.
526
527During the measurement, the /sys/device/cpu/freeze_on_smi will be set to
528freeze core counters on SMI.
529The aperf counter will not be effected by the setting.
530The cost of SMI can be measured by (aperf - unhalted core cycles).
531
532In practice, the percentages of SMI cycles is very useful for performance
533oriented analysis. --metric_only will be applied by default.
534The output is SMI cycles%, equals to (aperf - unhalted core cycles) / aperf
535
536Users who wants to get the actual value can apply --no-metric-only.
537
538--all-kernel::
539Configure all used events to run in kernel space.
540
541--all-user::
542Configure all used events to run in user space.
543
544--percore-show-thread::
545The event modifier "percore" has supported to sum up the event counts
546for all hardware threads in a core and show the counts per core.
547
548This option with event modifier "percore" enabled also sums up the event
549counts for all hardware threads in a core but show the sum counts per
550hardware thread. This is essentially a replacement for the any bit and
551convenient for post processing.
552
553--summary::
554Print summary for interval mode (-I).
555
556--no-csv-summary::
557Don't print 'summary' at the first column for CVS summary output.
558This option must be used with -x and --summary.
559
560This option can be enabled in perf config by setting the variable
561'stat.no-csv-summary'.
562
563$ perf config stat.no-csv-summary=true
564
565--cputype::
566Only enable events on applying cpu with this type for hybrid platform
567(e.g. core or atom)"
568
569EXAMPLES
570--------
571
572$ perf stat \-- make
573
574 Performance counter stats for 'make':
575
576 83723.452481 task-clock:u (msec) # 1.004 CPUs utilized
577 0 context-switches:u # 0.000 K/sec
578 0 cpu-migrations:u # 0.000 K/sec
579 3,228,188 page-faults:u # 0.039 M/sec
580 229,570,665,834 cycles:u # 2.742 GHz
581 313,163,853,778 instructions:u # 1.36 insn per cycle
582 69,704,684,856 branches:u # 832.559 M/sec
583 2,078,861,393 branch-misses:u # 2.98% of all branches
584
585 83.409183620 seconds time elapsed
586
587 74.684747000 seconds user
588 8.739217000 seconds sys
589
590TIMINGS
591-------
592As displayed in the example above we can display 3 types of timings.
593We always display the time the counters were enabled/alive:
594
595 83.409183620 seconds time elapsed
596
597For workload sessions we also display time the workloads spent in
598user/system lands:
599
600 74.684747000 seconds user
601 8.739217000 seconds sys
602
603Those times are the very same as displayed by the 'time' tool.
604
605CSV FORMAT
606----------
607
608With -x, perf stat is able to output a not-quite-CSV format output
609Commas in the output are not put into "". To make it easy to parse
610it is recommended to use a different character like -x \;
611
612The fields are in this order:
613
614 - optional usec time stamp in fractions of second (with -I xxx)
615 - optional CPU, core, or socket identifier
616 - optional number of logical CPUs aggregated
617 - counter value
618 - unit of the counter value or empty
619 - event name
620 - run time of counter
621 - percentage of measurement time the counter was running
622 - optional variance if multiple values are collected with -r
623 - optional metric value
624 - optional unit of metric
625
626Additional metrics may be printed with all earlier fields being empty.
627
628include::intel-hybrid.txt[]
629
630JSON FORMAT
631-----------
632
633With -j, perf stat is able to print out a JSON format output
634that can be used for parsing.
635
636- timestamp : optional usec time stamp in fractions of second (with -I)
637- optional aggregate options:
638 - core : core identifier (with --per-core)
639 - die : die identifier (with --per-die)
640 - socket : socket identifier (with --per-socket)
641 - node : node identifier (with --per-node)
642 - thread : thread identifier (with --per-thread)
643- counter-value : counter value
644- unit : unit of the counter value or empty
645- event : event name
646- variance : optional variance if multiple values are collected (with -r)
647- runtime : run time of counter
648- metric-value : optional metric value
649- metric-unit : optional unit of metric
650
651SEE ALSO
652--------
653linkperf:perf-top[1], linkperf:perf-list[1]