perf-stat - Online in the Cloud

PROGRAM:

NAME

perf-stat - Run a command and gather performance counter statistics

SYNOPSIS

perf stat [-e <EVENT> | --event=EVENT] [-a] <command>
perf stat [-e <EVENT> | --event=EVENT] [-a] — <command> [<options>]

DESCRIPTION

This command runs a command and gathers performance counter statistics from it.

OPTIONS

<command>...
Any command you can specify in a shell.

-e, --event=
Select the PMU event. Selection can be:

· a symbolic event name (use perf list to list all events)

· a raw PMU event (eventsel+umask) in the form of rNNN where NNN is a hexadecimal
event descriptor.

· a symbolically formed event like pmu/param1=0x3,param2/ where param1 and param2
are defined as formats for the PMU in
/sys/bus/event_sources/devices/<pmu>/format/*

· 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_sources/devices/<pmu>/format/*

-i, --no-inherit
child tasks do not inherit counters

-p, --pid=<pid>
stat events on existing process id (comma separated list)

-t, --tid=<tid>
stat events on existing thread id (comma separated list)

-a, --all-cpus
system-wide collection from all CPUs

-c, --scale
scale/normalize counter values

-r, --repeat=<n>
repeat command and print average + stddev (max: 100). 0 means forever.

-B, --big-num
print large numbers with thousands' separators according to locale

-C, --cpu=
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.

-A, --no-aggr
Do not aggregate counts across all monitored CPUs in system-wide mode (-a). This
option is only valid in system-wide mode.

-n, --null
null run - don’t start any counters

-v, --verbose
be more verbose (show counter open errors, etc)

-x SEP, --field-separator SEP
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.

-G name, --cgroup name
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.

-o file, --output file
Print the output into the designated file.

--append
Append to the output file designated with the -o option. Ignored if -o is not
specified.

--log-fd
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

--pre, --post
Pre and post measurement hooks, e.g.:

perf stat --repeat 10 --null --sync --pre make -s O=defconfig-build/clean — make -s -j64
O=defconfig-build/ bzImage

-I msecs, --interval-print msecs
Print count deltas every N milliseconds (minimum: 10ms) 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

--per-socket
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.

--per-core
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.

--per-thread
Aggregate counts per monitored threads, when monitoring threads (-t option) or
processes (-p option).

-D msecs, --delay msecs
After starting the program, wait msecs before measuring. This is useful to filter out
the startup phase of the program, which is often very different.

-T, --transaction
Print statistics of transactional execution if supported.

EXAMPLES

$ perf stat — make -j

Performance counter stats for 'make -j':

8117.370256 task clock ticks # 11.281 CPU utilization factor
678 context switches # 0.000 M/sec
133 CPU migrations # 0.000 M/sec
235724 pagefaults # 0.029 M/sec
24821162526 CPU cycles # 3057.784 M/sec
18687303457 instructions # 2302.138 M/sec
172158895 cache references # 21.209 M/sec
27075259 cache misses # 3.335 M/sec

Wall-clock time elapsed: 719.554352 msecs

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