NAME
perf-stat - Run a command and gather performance counter statisticsSYNOPSIS
perf stat [-e <EVENT> | --event=EVENT] [-a] <command> perf stat [-e <EVENT> | --event=EVENT] [-a] -- <command> [<options>] perf stat [-e <EVENT> | --event=EVENT] [-a] record [-o file] -- <command> [<options>] perf stat report [-i file]
DESCRIPTION
This command runs a command and gathers performance counter statistics from it.OPTIONS
<command>...Any command you can specify in a shell.
See STAT RECORD.
See STAT REPORT.
Select the PMU event. Selection can be:
•a symbolic event name (use perf
list to list all events)
•a raw PMU event in the form of rN
where N is a hexadecimal value that represents the raw register encoding with
the layout of the event control registers as described by entries in
/sys/bus/event_source/devices/cpu/format/*.
•a symbolic or raw PMU event followed
by an optional colon and a list of event modifiers, e.g., cpu-cycles:p. See
the perf-list(1) man page for details on event modifiers.
•a symbolically formed event like
pmu/param1=0x3,param2/ where param1 and param2 are defined as formats
for the PMU in /sys/bus/event_source/devices/<pmu>/format/*
'percore' is a event qualifier that sums up the event counts for both hardware threads in a core. For example: perf stat -A -a -e cpu/event,percore=1/,otherevent ...
•a symbolically formed event like
pmu/config=M,config1=N,config2=K/ where M, N, K are numbers (in
decimal, hex, octal format). Acceptable values for each of config,
config1 and config2 parameters are defined by corresponding
entries in /sys/bus/event_source/devices/<pmu>/format/*
Note that the last two syntaxes support prefix and glob matching in the PMU name to simplify creation of events across multiple instances of the same type of PMU in large systems (e.g. memory controller PMUs). Multiple PMU instances are typical for uncore PMUs, so the prefix 'uncore_' is also ignored when performing this match.
child tasks do not inherit counters
stat events on existing process id (comma
separated list)
stat events on existing thread id (comma
separated list)
stat events on existing bpf program id (comma
separated list), requiring root rights. bpftool-prog could be used to find
program id all bpf programs in the system. For example:
# bpftool prog | head -n 1 17247: tracepoint name sys_enter tag 192d548b9d754067 gpl
# perf stat -e cycles,instructions --bpf-prog 17247 --timeout 1000
Performance counter stats for 'BPF program(s) 17247':
85,967 cycles 28,982 instructions # 0.34 insn per cycle
1.102235068 seconds time elapsed
Use BPF programs to aggregate readings from
perf_events. This allows multiple perf-stat sessions that are counting the
same metric (cycles, instructions, etc.) to share hardware counters. To use
BPF programs on common events by default, use "perf config
stat.bpf-counter-events=<list_of_events>".
With option "--bpf-counters",
different perf-stat sessions share information about shared BPF programs and
maps via a pinned hashmap. Use "--bpf-attr-map" to specify the path
of this pinned hashmap. The default path is /sys/fs/bpf/perf_attr_map.
system-wide collection from all CPUs (default
if no target is specified)
Don’t scale/normalize counter
values
print more detailed statistics, can be
specified up to 3 times
-d: detailed events, L1 and LLC data cache -d -d: more detailed events, dTLB and iTLB events -d -d -d: very detailed events, adding prefetch events
repeat command and print average + stddev
(max: 100). 0 means forever.
print large numbers with thousands' separators according to locale. Enabled by default. Use "--no-big-num" to disable. Default setting can be changed with "perf config stat.big-num=false".
Count only on the list of CPUs provided.
Multiple CPUs can be provided as a comma-separated list with no space: 0,1.
Ranges of CPUs are specified with -: 0-2. In per-thread mode, this option is
ignored. The -a option is still necessary to activate system-wide monitoring.
Default is to count on all CPUs.
Do not aggregate counts across all monitored
CPUs.
null run - Don’t start any
counters.
be more verbose (show counter open errors,
etc)
print counts using a CSV-style output to make
it easy to import directly into spreadsheets. Columns are separated by the
string specified in SEP.
Display time for each run (-r option), in a
table format, e.g.:
$ perf stat --null -r 5 --table perf bench sched pipe
Performance counter stats for 'perf bench sched pipe' (5 runs):
# Table of individual measurements: 5.189 (-0.293) # 5.189 (-0.294) # 5.186 (-0.296) # 5.663 (+0.181) ## 6.186 (+0.703) ####
# Final result: 5.483 +- 0.198 seconds time elapsed ( +- 3.62% )
monitor only in the container (cgroup) called
"name". This option is available only in per-cpu mode. The cgroup
filesystem must be mounted. All threads belonging to container
"name" are monitored when they run on the monitored CPUs. Multiple
cgroups can be provided. Each cgroup is applied to the corresponding event,
i.e., first cgroup to first event, second cgroup to second event and so on. It
is possible to provide an empty cgroup (monitor all the time) using, e.g., -G
foo,,bar. Cgroups must have corresponding events, i.e., they always refer to
events defined earlier on the command line. If the user wants to track
multiple events for a specific cgroup, the user can use -e e1 -e e2 -G
foo,foo or just use -e e1 -e e2 -G foo.
Expand event list for each cgroup in
"name" (allow multiple cgroups separated by comma). It also support
regex patterns to match multiple groups. This has same effect that repeating
-e option and -G option for each event x name. This option cannot be used with
-G/--cgroup option.
Print the output into the designated
file.
Append to the output file designated with the
-o option. Ignored if -o is not specified.
Log output to fd, instead of stderr.
Complementary to --output, and mutually exclusive with it. --append may be
used here. Examples: 3>results perf stat --log-fd 3 -- $cmd
3>>results perf stat --log-fd 3 --append -- $cmd
ctl-fifo / ack-fifo are opened and used as
ctl-fd / ack-fd as follows. Listen on ctl-fd descriptor for command to control
measurement ( enable: enable events, disable: disable events).
Measurements can be started with events disabled using --delay=-1 option.
Optionally send control command completion ( ack\n) to ack-fd
descriptor to synchronize with the controlling process. Example of bash shell
script to enable and disable events during measurements:
#!/bin/bash
ctl_dir=/tmp/
ctl_fifo=${ctl_dir}perf_ctl.fifo test -p ${ctl_fifo} && unlink ${ctl_fifo} mkfifo ${ctl_fifo} exec {ctl_fd}<>${ctl_fifo}
ctl_ack_fifo=${ctl_dir}perf_ctl_ack.fifo test -p ${ctl_ack_fifo} && unlink ${ctl_ack_fifo} mkfifo ${ctl_ack_fifo} exec {ctl_fd_ack}<>${ctl_ack_fifo}
perf stat -D -1 -e cpu-cycles -a -I 1000 \ --control fd:${ctl_fd},${ctl_fd_ack} \ \-- sleep 30 & perf_pid=$!
sleep 5 && echo 'enable' >&${ctl_fd} && read -u ${ctl_fd_ack} e1 && echo "enabled(${e1})" sleep 10 && echo 'disable' >&${ctl_fd} && read -u ${ctl_fd_ack} d1 && echo "disabled(${d1})"
exec {ctl_fd_ack}>&- unlink ${ctl_ack_fifo}
exec {ctl_fd}>&- unlink ${ctl_fifo}
wait -n ${perf_pid} exit $?
Pre and post measurement hooks, e.g.:
Print count deltas every N milliseconds
(minimum: 1ms) The overhead percentage could be high in some cases, for
instance with small, sub 100ms intervals. Use with caution. example: perf
stat -I 1000 -e cycles -a sleep 5
Print count deltas for fixed number of times.
This option should be used together with "-I" option. example:
perf stat -I 1000 --interval-count 2 -e cycles -a
Clear the screen before next interval.
Stop the perf stat session and print
count deltas after N milliseconds (minimum: 10 ms). This option is not
supported with the "-I" option. example: perf stat --time 2000 -e
cycles -a
Only print computed metrics. Print them in a
single line. Don’t show any raw values. Not supported with
--per-thread.
Aggregate counts per processor socket for
system-wide mode measurements. This is a useful mode to detect imbalance
between sockets. To enable this mode, use --per-socket in addition to -a.
(system-wide). The output includes the socket number and the number of online
processors on that socket. This is useful to gauge the amount of
aggregation.
Aggregate counts per processor die for
system-wide mode measurements. This is a useful mode to detect imbalance
between dies. To enable this mode, use --per-die in addition to -a.
(system-wide). The output includes the die number and the number of online
processors on that die. This is useful to gauge the amount of
aggregation.
Aggregate counts per physical processor for
system-wide mode measurements. This is a useful mode to detect imbalance
between physical cores. To enable this mode, use --per-core in addition to -a.
(system-wide). The output includes the core number and the number of online
logical processors on that physical processor.
Aggregate counts per monitored threads, when
monitoring threads (-t option) or processes (-p option).
Aggregate counts per NUMA nodes for
system-wide mode measurements. This is a useful mode to detect imbalance
between NUMA nodes. To enable this mode, use --per-node in addition to -a.
(system-wide).
After starting the program, wait msecs before
measuring (-1: start with events disabled). This is useful to filter out the
startup phase of the program, which is often very different.
Print statistics of transactional execution if
supported.
By default, events to compute a metric are
placed in weak groups. The group tries to enforce scheduling all or none of
the events. The --metric-no-group option places events outside of groups and
may increase the chance of the event being scheduled - leading to more
accuracy. However, as events may not be scheduled together accuracy for
metrics like instructions per cycle can be lower - as both metrics may no
longer be being measured at the same time.
By default metric events in different weak
groups can be shared if one group contains all the events needed by another.
In such cases one group will be eliminated reducing event multiplexing and
making it so that certain groups of metrics sum to 100%. A downside to sharing
a group is that the group may require multiplexing and so accuracy for a small
group that need not have multiplexing is lowered. This option forbids the
event merging logic from sharing events between groups and may be used to
increase accuracy in this case.
Don’t print output, warnings or
messages. This is useful with perf stat record below to only write data to the
perf.data file.
STAT RECORD
Stores stat data into perf data file.Output file name.
STAT REPORT
Reads and reports stat data from perf data file.Input file name.
Aggregate counts per processor socket for
system-wide mode measurements.
Aggregate counts per processor die for
system-wide mode measurements.
Aggregate counts per physical processor for
system-wide mode measurements.
Print metrics or metricgroups specified in a
comma separated list. For a group all metrics from the group are added. The
events from the metrics are automatically measured. See perf list output for
the possible metrics and metricgroups.
Do not aggregate counts across all monitored
CPUs.
Print complete top-down metrics supported by
the CPU. This allows to determine bottle necks in the CPU pipeline for CPU
bound workloads, by breaking the cycles consumed down into frontend bound,
backend bound, bad speculation and retiring.
Print the top-down statistics that equal to or
lower than the input level. It allows users to print the interested top-down
metrics level instead of the complete top-down metrics.
Do not merge results from same PMUs.
Merge the hybrid event counts from all
PMUs.
Measure SMI cost if msr/aperf/ and msr/smi/
events are supported.
Configure all used events to run in kernel
space.
Configure all used events to run in user
space.
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.
Print summary for interval mode (-I).
Don’t print summary at the first
column for CVS summary output. This option must be used with -x and
--summary.
Only enable events on applying cpu with this
type for hybrid platform (e.g. core or atom)"
EXAMPLES
$ perf stat -- makePerformance 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
74.684747000 seconds user 8.739217000 seconds sys
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 \;•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
INTEL HYBRID SUPPORT
Support for Intel hybrid events within perf tools.cpu_core/<event name>/ or cpu_atom/<event name>/
perf stat -e cpu_core/cycles/
------------------------------------------------------------ perf_event_attr: size 120 config 0x400000000 sample_type IDENTIFIER read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING disabled 1 inherit 1 exclude_guest 1 ------------------------------------------------------------
------------------------------------------------------------ perf_event_attr: size 120 config 0x800000000 sample_type IDENTIFIER read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING disabled 1 inherit 1 exclude_guest 1 ------------------------------------------------------------
Performance counter stats for 'system wide':
6,744,979 cpu_core/cycles/ 1,965,552 cpu_atom/cycles/
perf_event_attr: size 120 config 0x400000000 sample_type IDENTIFIER read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING disabled 1 inherit 1 enable_on_exec 1 exclude_guest 1
perf_event_attr: size 120 config 0x800000000 sample_type IDENTIFIER read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING disabled 1 inherit 1 enable_on_exec 1 exclude_guest 1
Performance counter stats for 'taskset -c 16 ./triad_loop':
233,066,666 cpu_core/cycles/ (0.43%) 604,097,080 cpu_atom/cycles/ (99.57%)
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
perf-top(1), perf-list(1)2024-06-21 | perf |