646 lines
23 KiB
Plaintext
646 lines
23 KiB
Plaintext
perf-stat(1)
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============
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NAME
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----
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perf-stat - Run a command and gather performance counter statistics
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SYNOPSIS
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--------
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[verse]
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'perf stat' [-e <EVENT> | --event=EVENT] [-a] <command>
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'perf stat' [-e <EVENT> | --event=EVENT] [-a] \-- <command> [<options>]
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'perf stat' [-e <EVENT> | --event=EVENT] [-a] record [-o file] \-- <command> [<options>]
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'perf stat' report [-i file]
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DESCRIPTION
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-----------
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This command runs a command and gathers performance counter statistics
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from it.
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OPTIONS
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-------
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<command>...::
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Any command you can specify in a shell.
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record::
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See STAT RECORD.
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report::
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See STAT REPORT.
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-e::
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--event=::
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Select the PMU event. Selection can be:
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- a symbolic event name (use 'perf list' to list all events)
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- a raw PMU event in the form of rN where N is a hexadecimal value
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that represents the raw register encoding with the layout of the
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event control registers as described by entries in
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/sys/bus/event_source/devices/cpu/format/*.
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- a symbolic or raw PMU event followed by an optional colon
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and a list of event modifiers, e.g., cpu-cycles:p. See the
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linkperf:perf-list[1] man page for details on event modifiers.
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- a symbolically formed event like 'pmu/param1=0x3,param2/' where
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param1 and param2 are defined as formats for the PMU in
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/sys/bus/event_source/devices/<pmu>/format/*
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'percore' is a event qualifier that sums up the event counts for both
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hardware threads in a core. For example:
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perf stat -A -a -e cpu/event,percore=1/,otherevent ...
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- a symbolically formed event like 'pmu/config=M,config1=N,config2=K/'
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where M, N, K are numbers (in decimal, hex, octal format).
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Acceptable values for each of 'config', 'config1' and 'config2'
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parameters are defined by corresponding entries in
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/sys/bus/event_source/devices/<pmu>/format/*
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Note that the last two syntaxes support prefix and glob matching in
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the PMU name to simplify creation of events across multiple instances
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of the same type of PMU in large systems (e.g. memory controller PMUs).
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Multiple PMU instances are typical for uncore PMUs, so the prefix
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'uncore_' is also ignored when performing this match.
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-i::
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--no-inherit::
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child tasks do not inherit counters
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-p::
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--pid=<pid>::
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stat events on existing process id (comma separated list)
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-t::
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--tid=<tid>::
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stat events on existing thread id (comma separated list)
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-b::
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--bpf-prog::
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stat events on existing bpf program id (comma separated list),
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requiring root rights. bpftool-prog could be used to find program
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id all bpf programs in the system. For example:
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# bpftool prog | head -n 1
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17247: tracepoint name sys_enter tag 192d548b9d754067 gpl
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# perf stat -e cycles,instructions --bpf-prog 17247 --timeout 1000
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Performance counter stats for 'BPF program(s) 17247':
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85,967 cycles
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28,982 instructions # 0.34 insn per cycle
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1.102235068 seconds time elapsed
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--bpf-counters::
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Use BPF programs to aggregate readings from perf_events. This
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allows multiple perf-stat sessions that are counting the same metric (cycles,
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instructions, etc.) to share hardware counters.
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To use BPF programs on common events by default, use
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"perf config stat.bpf-counter-events=<list_of_events>".
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--bpf-attr-map::
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With option "--bpf-counters", different perf-stat sessions share
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information about shared BPF programs and maps via a pinned hashmap.
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Use "--bpf-attr-map" to specify the path of this pinned hashmap.
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The default path is /sys/fs/bpf/perf_attr_map.
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ifdef::HAVE_LIBPFM[]
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--pfm-events events::
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Select a PMU event using libpfm4 syntax (see http://perfmon2.sf.net)
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including support for event filters. For example '--pfm-events
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inst_retired:any_p:u:c=1:i'. More than one event can be passed to the
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option using the comma separator. Hardware events and generic hardware
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events cannot be mixed together. The latter must be used with the -e
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option. The -e option and this one can be mixed and matched. Events
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can be grouped using the {} notation.
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endif::HAVE_LIBPFM[]
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-a::
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--all-cpus::
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system-wide collection from all CPUs (default if no target is specified)
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--no-scale::
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Don't scale/normalize counter values
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-d::
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--detailed::
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print more detailed statistics, can be specified up to 3 times
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-d: detailed events, L1 and LLC data cache
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-d -d: more detailed events, dTLB and iTLB events
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-d -d -d: very detailed events, adding prefetch events
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-r::
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--repeat=<n>::
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repeat command and print average + stddev (max: 100). 0 means forever.
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-B::
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--big-num::
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print large numbers with thousands' separators according to locale.
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Enabled by default. Use "--no-big-num" to disable.
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Default setting can be changed with "perf config stat.big-num=false".
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-C::
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--cpu=::
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Count only on the list of CPUs provided. Multiple CPUs can be provided as a
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comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2.
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In per-thread mode, this option is ignored. The -a option is still necessary
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to activate system-wide monitoring. Default is to count on all CPUs.
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-A::
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--no-aggr::
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Do not aggregate counts across all monitored CPUs.
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-n::
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--null::
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null run - Don't start any counters.
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This can be useful to measure just elapsed wall-clock time - or to assess the
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raw overhead of perf stat itself, without running any counters.
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-v::
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--verbose::
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be more verbose (show counter open errors, etc)
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-x SEP::
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--field-separator SEP::
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print counts using a CSV-style output to make it easy to import directly into
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spreadsheets. Columns are separated by the string specified in SEP.
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--table:: Display time for each run (-r option), in a table format, e.g.:
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$ perf stat --null -r 5 --table perf bench sched pipe
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Performance counter stats for 'perf bench sched pipe' (5 runs):
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# Table of individual measurements:
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5.189 (-0.293) #
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5.189 (-0.294) #
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5.186 (-0.296) #
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5.663 (+0.181) ##
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6.186 (+0.703) ####
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# Final result:
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5.483 +- 0.198 seconds time elapsed ( +- 3.62% )
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-G name::
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--cgroup name::
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monitor only in the container (cgroup) called "name". This option is available only
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in per-cpu mode. The cgroup filesystem must be mounted. All threads belonging to
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container "name" are monitored when they run on the monitored CPUs. Multiple cgroups
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can be provided. Each cgroup is applied to the corresponding event, i.e., first cgroup
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to first event, second cgroup to second event and so on. It is possible to provide
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an empty cgroup (monitor all the time) using, e.g., -G foo,,bar. Cgroups must have
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corresponding events, i.e., they always refer to events defined earlier on the command
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line. If the user wants to track multiple events for a specific cgroup, the user can
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use '-e e1 -e e2 -G foo,foo' or just use '-e e1 -e e2 -G foo'.
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If wanting to monitor, say, 'cycles' for a cgroup and also for system wide, this
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command line can be used: 'perf stat -e cycles -G cgroup_name -a -e cycles'.
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--for-each-cgroup name::
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Expand event list for each cgroup in "name" (allow multiple cgroups separated
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by comma). It also support regex patterns to match multiple groups. This has same
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effect that repeating -e option and -G option for each event x name. This option
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cannot be used with -G/--cgroup option.
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-o file::
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--output file::
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Print the output into the designated file.
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--append::
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Append to the output file designated with the -o option. Ignored if -o is not specified.
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--log-fd::
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Log output to fd, instead of stderr. Complementary to --output, and mutually exclusive
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with it. --append may be used here. Examples:
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3>results perf stat --log-fd 3 \-- $cmd
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3>>results perf stat --log-fd 3 --append \-- $cmd
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--control=fifo:ctl-fifo[,ack-fifo]::
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--control=fd:ctl-fd[,ack-fd]::
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ctl-fifo / ack-fifo are opened and used as ctl-fd / ack-fd as follows.
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Listen on ctl-fd descriptor for command to control measurement ('enable': enable events,
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'disable': disable events). Measurements can be started with events disabled using
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--delay=-1 option. Optionally send control command completion ('ack\n') to ack-fd descriptor
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to synchronize with the controlling process. Example of bash shell script to enable and
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disable events during measurements:
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#!/bin/bash
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ctl_dir=/tmp/
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ctl_fifo=${ctl_dir}perf_ctl.fifo
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test -p ${ctl_fifo} && unlink ${ctl_fifo}
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mkfifo ${ctl_fifo}
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exec {ctl_fd}<>${ctl_fifo}
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ctl_ack_fifo=${ctl_dir}perf_ctl_ack.fifo
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test -p ${ctl_ack_fifo} && unlink ${ctl_ack_fifo}
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mkfifo ${ctl_ack_fifo}
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exec {ctl_fd_ack}<>${ctl_ack_fifo}
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perf stat -D -1 -e cpu-cycles -a -I 1000 \
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--control fd:${ctl_fd},${ctl_fd_ack} \
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\-- sleep 30 &
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perf_pid=$!
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sleep 5 && echo 'enable' >&${ctl_fd} && read -u ${ctl_fd_ack} e1 && echo "enabled(${e1})"
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sleep 10 && echo 'disable' >&${ctl_fd} && read -u ${ctl_fd_ack} d1 && echo "disabled(${d1})"
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exec {ctl_fd_ack}>&-
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unlink ${ctl_ack_fifo}
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exec {ctl_fd}>&-
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unlink ${ctl_fifo}
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wait -n ${perf_pid}
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exit $?
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--pre::
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--post::
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Pre and post measurement hooks, e.g.:
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perf stat --repeat 10 --null --sync --pre 'make -s O=defconfig-build/clean' \-- make -s -j64 O=defconfig-build/ bzImage
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-I msecs::
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--interval-print msecs::
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Print count deltas every N milliseconds (minimum: 1ms)
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The overhead percentage could be high in some cases, for instance with small, sub 100ms intervals. Use with caution.
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example: 'perf stat -I 1000 -e cycles -a sleep 5'
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If the metric exists, it is calculated by the counts generated in this interval and the metric is printed after #.
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--interval-count times::
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Print count deltas for fixed number of times.
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This option should be used together with "-I" option.
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example: 'perf stat -I 1000 --interval-count 2 -e cycles -a'
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--interval-clear::
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Clear the screen before next interval.
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--timeout msecs::
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Stop the 'perf stat' session and print count deltas after N milliseconds (minimum: 10 ms).
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This option is not supported with the "-I" option.
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example: 'perf stat --time 2000 -e cycles -a'
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--metric-only::
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Only print computed metrics. Print them in a single line.
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Don't show any raw values. Not supported with --per-thread.
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--per-socket::
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Aggregate counts per processor socket for system-wide mode measurements. This
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is a useful mode to detect imbalance between sockets. To enable this mode,
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use --per-socket in addition to -a. (system-wide). The output includes the
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socket number and the number of online processors on that socket. This is
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useful to gauge the amount of aggregation.
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--per-die::
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Aggregate counts per processor die for system-wide mode measurements. This
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is a useful mode to detect imbalance between dies. To enable this mode,
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use --per-die in addition to -a. (system-wide). The output includes the
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die number and the number of online processors on that die. This is
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useful to gauge the amount of aggregation.
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--per-cluster::
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Aggregate counts per processor cluster for system-wide mode measurement. This
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is a useful mode to detect imbalance between clusters. To enable this mode,
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use --per-cluster in addition to -a. (system-wide). The output includes the
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cluster number and the number of online processors on that cluster. This is
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useful to gauge the amount of aggregation. The information of cluster ID and
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related CPUs can be gotten from /sys/devices/system/cpu/cpuX/topology/cluster_{id, cpus}.
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--per-cache::
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Aggregate counts per cache instance for system-wide mode measurements. By
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default, the aggregation happens for the cache level at the highest index
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in the system. To specify a particular level, mention the cache level
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alongside the option in the format [Ll][1-9][0-9]*. For example:
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Using option "--per-cache=l3" or "--per-cache=L3" will aggregate the
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information at the boundary of the level 3 cache in the system.
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--per-core::
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Aggregate counts per physical processor for system-wide mode measurements. This
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is a useful mode to detect imbalance between physical cores. To enable this mode,
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use --per-core in addition to -a. (system-wide). The output includes the
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core number and the number of online logical processors on that physical processor.
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--per-thread::
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Aggregate counts per monitored threads, when monitoring threads (-t option)
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or processes (-p option).
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--per-node::
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Aggregate counts per NUMA nodes for system-wide mode measurements. This
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is a useful mode to detect imbalance between NUMA nodes. To enable this
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mode, use --per-node in addition to -a. (system-wide).
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-D msecs::
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--delay msecs::
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After starting the program, wait msecs before measuring (-1: start with events
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disabled). This is useful to filter out the startup phase of the program,
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which is often very different.
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-T::
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--transaction::
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Print statistics of transactional execution if supported.
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--metric-no-group::
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By default, events to compute a metric are placed in weak groups. The
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group tries to enforce scheduling all or none of the events. The
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--metric-no-group option places events outside of groups and may
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increase the chance of the event being scheduled - leading to more
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accuracy. However, as events may not be scheduled together accuracy
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for metrics like instructions per cycle can be lower - as both metrics
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may no longer be being measured at the same time.
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--metric-no-merge::
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By default metric events in different weak groups can be shared if one
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group contains all the events needed by another. In such cases one
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group will be eliminated reducing event multiplexing and making it so
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that certain groups of metrics sum to 100%. A downside to sharing a
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group is that the group may require multiplexing and so accuracy for a
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small group that need not have multiplexing is lowered. This option
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forbids the event merging logic from sharing events between groups and
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may be used to increase accuracy in this case.
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--metric-no-threshold::
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Metric thresholds may increase the number of events necessary to
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compute whether a metric has exceeded its threshold expression. This
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may not be desirable, for example, as the events can introduce
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multiplexing. This option disables the adding of threshold expression
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events for a metric. However, if there are sufficient events to
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compute the threshold then the threshold is still computed and used to
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color the metric's computed value.
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--quiet::
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Don't print output, warnings or messages. This is useful with perf stat
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record below to only write data to the perf.data file.
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STAT RECORD
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-----------
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Stores stat data into perf data file.
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-o file::
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--output file::
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Output file name.
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STAT REPORT
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-----------
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Reads and reports stat data from perf data file.
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-i file::
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--input file::
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Input file name.
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--per-socket::
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Aggregate counts per processor socket for system-wide mode measurements.
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--per-die::
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Aggregate counts per processor die for system-wide mode measurements.
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--per-cluster::
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Aggregate counts perf processor cluster for system-wide mode measurements.
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--per-cache::
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Aggregate counts per cache instance for system-wide mode measurements. By
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default, the aggregation happens for the cache level at the highest index
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in the system. To specify a particular level, mention the cache level
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alongside the option in the format [Ll][1-9][0-9]*. For example: Using
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option "--per-cache=l3" or "--per-cache=L3" will aggregate the
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information at the boundary of the level 3 cache in the system.
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--per-core::
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Aggregate counts per physical processor for system-wide mode measurements.
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-M::
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--metrics::
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Print metrics or metricgroups specified in a comma separated list.
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For a group all metrics from the group are added.
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The events from the metrics are automatically measured.
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See perf list output for the possible metrics and metricgroups.
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When threshold information is available for a metric, the
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color red is used to signify a metric has exceeded a threshold
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while green shows it hasn't. The default color means that
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no threshold information was available or the threshold
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couldn't be computed.
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-A::
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--no-aggr::
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--no-merge::
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Do not aggregate/merge counts across monitored CPUs or PMUs.
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When multiple events are created from a single event specification,
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stat will, by default, aggregate the event counts and show the result
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in a single row. This option disables that behavior and shows the
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individual events and counts.
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Multiple events are created from a single event specification when:
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1. PID monitoring isn't requested and the system has more than one
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CPU. For example, a system with 8 SMT threads will have one event
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opened on each thread and aggregation is performed across them.
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2. Prefix or glob wildcard matching is used for the PMU name. For
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example, multiple memory controller PMUs may exist typically with a
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suffix of _0, _1, etc. By default the event counts will all be
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combined if the PMU is specified without the suffix such as
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uncore_imc rather than uncore_imc_0.
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3. Aliases, which are listed immediately after the Kernel PMU events
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by perf list, are used.
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--hybrid-merge::
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Merge core event counts from all core PMUs. In hybrid or big.LITTLE
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systems by default each core PMU will report its count
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separately. This option forces core PMU counts to be combined to give
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a behavior closer to having a single CPU type in the system.
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--topdown::
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Print top-down metrics supported by the CPU. This allows to determine
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bottle necks in the CPU pipeline for CPU bound workloads, by breaking
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the cycles consumed down into frontend bound, backend bound, bad
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speculation and retiring.
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Frontend bound means that the CPU cannot fetch and decode instructions fast
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enough. Backend bound means that computation or memory access is the bottle
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neck. Bad Speculation means that the CPU wasted cycles due to branch
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mispredictions and similar issues. Retiring means that the CPU computed without
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an apparently bottleneck. The bottleneck is only the real bottleneck
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if the workload is actually bound by the CPU and not by something else.
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For best results it is usually a good idea to use it with interval
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mode like -I 1000, as the bottleneck of workloads can change often.
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This enables --metric-only, unless overridden with --no-metric-only.
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The following restrictions only apply to older Intel CPUs and Atom,
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on newer CPUs (IceLake and later) TopDown can be collected for any thread:
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The top down metrics are collected per core instead of per
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CPU thread. Per core mode is automatically enabled
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|
and -a (global monitoring) is needed, requiring root rights or
|
|
perf.perf_event_paranoid=-1.
|
|
|
|
Topdown uses the full Performance Monitoring Unit, and needs
|
|
disabling of the NMI watchdog (as root):
|
|
echo 0 > /proc/sys/kernel/nmi_watchdog
|
|
for best results. Otherwise the bottlenecks may be inconsistent
|
|
on workload with changing phases.
|
|
|
|
To interpret the results it is usually needed to know on which
|
|
CPUs the workload runs on. If needed the CPUs can be forced using
|
|
taskset.
|
|
|
|
--td-level::
|
|
Print the top-down statistics that equal the input level. It allows
|
|
users to print the interested top-down metrics level instead of the
|
|
level 1 top-down metrics.
|
|
|
|
As the higher levels gather more metrics and use more counters they
|
|
will be less accurate. By convention a metric can be examined by
|
|
appending '_group' to it and this will increase accuracy compared to
|
|
gathering all metrics for a level. For example, level 1 analysis may
|
|
highlight 'tma_frontend_bound'. This metric may be drilled into with
|
|
'tma_frontend_bound_group' with
|
|
'perf stat -M tma_frontend_bound_group...'.
|
|
|
|
Error out if the input is higher than the supported max level.
|
|
|
|
--smi-cost::
|
|
Measure SMI cost if msr/aperf/ and msr/smi/ events are supported.
|
|
|
|
During the measurement, the /sys/device/cpu/freeze_on_smi will be set to
|
|
freeze core counters on SMI.
|
|
The aperf counter will not be effected by the setting.
|
|
The cost of SMI can be measured by (aperf - unhalted core cycles).
|
|
|
|
In practice, the percentages of SMI cycles is very useful for performance
|
|
oriented analysis. --metric_only will be applied by default.
|
|
The output is SMI cycles%, equals to (aperf - unhalted core cycles) / aperf
|
|
|
|
Users who wants to get the actual value can apply --no-metric-only.
|
|
|
|
--all-kernel::
|
|
Configure all used events to run in kernel space.
|
|
|
|
--all-user::
|
|
Configure all used events to run in user space.
|
|
|
|
--percore-show-thread::
|
|
The event modifier "percore" has supported to sum up the event counts
|
|
for all hardware threads in a core and show the counts per core.
|
|
|
|
This option with event modifier "percore" enabled also sums up the event
|
|
counts for all hardware threads in a core but show the sum counts per
|
|
hardware thread. This is essentially a replacement for the any bit and
|
|
convenient for post processing.
|
|
|
|
--summary::
|
|
Print summary for interval mode (-I).
|
|
|
|
--no-csv-summary::
|
|
Don't print 'summary' at the first column for CVS summary output.
|
|
This option must be used with -x and --summary.
|
|
|
|
This option can be enabled in perf config by setting the variable
|
|
'stat.no-csv-summary'.
|
|
|
|
$ perf config stat.no-csv-summary=true
|
|
|
|
--cputype::
|
|
Only enable events on applying cpu with this type for hybrid platform
|
|
(e.g. core or atom)"
|
|
|
|
EXAMPLES
|
|
--------
|
|
|
|
$ perf stat \-- make
|
|
|
|
Performance counter stats for 'make':
|
|
|
|
83723.452481 task-clock:u (msec) # 1.004 CPUs utilized
|
|
0 context-switches:u # 0.000 K/sec
|
|
0 cpu-migrations:u # 0.000 K/sec
|
|
3,228,188 page-faults:u # 0.039 M/sec
|
|
229,570,665,834 cycles:u # 2.742 GHz
|
|
313,163,853,778 instructions:u # 1.36 insn per cycle
|
|
69,704,684,856 branches:u # 832.559 M/sec
|
|
2,078,861,393 branch-misses:u # 2.98% of all branches
|
|
|
|
83.409183620 seconds time elapsed
|
|
|
|
74.684747000 seconds user
|
|
8.739217000 seconds sys
|
|
|
|
TIMINGS
|
|
-------
|
|
As displayed in the example above we can display 3 types of timings.
|
|
We always display the time the counters were enabled/alive:
|
|
|
|
83.409183620 seconds time elapsed
|
|
|
|
For workload sessions we also display time the workloads spent in
|
|
user/system lands:
|
|
|
|
74.684747000 seconds user
|
|
8.739217000 seconds sys
|
|
|
|
Those times are the very same as displayed by the 'time' tool.
|
|
|
|
CSV FORMAT
|
|
----------
|
|
|
|
With -x, perf stat is able to output a not-quite-CSV format output
|
|
Commas in the output are not put into "". To make it easy to parse
|
|
it is recommended to use a different character like -x \;
|
|
|
|
The fields are in this order:
|
|
|
|
- optional usec time stamp in fractions of second (with -I xxx)
|
|
- optional CPU, core, or socket identifier
|
|
- optional number of logical CPUs aggregated
|
|
- counter value
|
|
- unit of the counter value or empty
|
|
- event name
|
|
- run time of counter
|
|
- percentage of measurement time the counter was running
|
|
- optional variance if multiple values are collected with -r
|
|
- optional metric value
|
|
- optional unit of metric
|
|
|
|
Additional metrics may be printed with all earlier fields being empty.
|
|
|
|
include::intel-hybrid.txt[]
|
|
|
|
JSON FORMAT
|
|
-----------
|
|
|
|
With -j, perf stat is able to print out a JSON format output
|
|
that can be used for parsing.
|
|
|
|
- timestamp : optional usec time stamp in fractions of second (with -I)
|
|
- optional aggregate options:
|
|
- core : core identifier (with --per-core)
|
|
- die : die identifier (with --per-die)
|
|
- socket : socket identifier (with --per-socket)
|
|
- node : node identifier (with --per-node)
|
|
- thread : thread identifier (with --per-thread)
|
|
- counter-value : counter value
|
|
- unit : unit of the counter value or empty
|
|
- event : event name
|
|
- variance : optional variance if multiple values are collected (with -r)
|
|
- runtime : run time of counter
|
|
- metric-value : optional metric value
|
|
- metric-unit : optional unit of metric
|
|
|
|
SEE ALSO
|
|
--------
|
|
linkperf:perf-top[1], linkperf:perf-list[1]
|