perf-stat(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | STAT RECORD | STAT REPORT | EXAMPLES | TIMINGS | CSV FORMAT | INTEL HYBRID SUPPORT | JSON FORMAT | SEE ALSO | COLOPHON

PERF-STAT(1)                   perf Manual                  PERF-STAT(1)

NAME         top

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

SYNOPSIS         top

       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         top

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

OPTIONS         top

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

       record
           See STAT RECORD.

       report
           See STAT REPORT.

       -e, --event=
           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.

       -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)

       -b, --bpf-prog
           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

       --bpf-counters
           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>".

       --bpf-attr-map
           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.

       -a, --all-cpus
           system-wide collection from all CPUs (default if no target is
           specified)

       --no-scale
           Don’t scale/normalize counter values

       -d, --detailed
           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

       -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. Enabled by default. Use "--no-big-num" to disable.
           Default setting can be changed with "perf config
           stat.big-num=false".

       -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.

       -n, --null
           null run - Don’t start any counters.

       This can be useful to measure just elapsed wall-clock time - or
       to assess the raw overhead of perf stat itself, without running
       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.

       --table
           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% )

       -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. 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.

       If wanting to monitor, say, cycles for a cgroup and also for
       system wide, this command line can be used: perf stat -e cycles
       -G cgroup_name -a -e cycles.

       --for-each-cgroup name
           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.

       -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

       --control=fifo:ctl-fifo[,ack-fifo], --control=fd:ctl-fd[,ack-fd]
           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, --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: 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

       If the metric exists, it is calculated by the counts generated in
       this interval and the metric is printed after #.

       --interval-count times
           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

       --interval-clear
           Clear the screen before next interval.

       --timeout msecs
           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

       --metric-only
           Only print computed metrics. Print them in a single line.
           Don’t show any raw values. Not supported with --per-thread.

       --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-die
           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.

       --per-cluster
           Aggregate counts per processor cluster for system-wide mode
           measurement. This is a useful mode to detect imbalance
           between clusters. To enable this mode, use --per-cluster in
           addition to -a. (system-wide). The output includes the
           cluster number and the number of online processors on that
           cluster. This is useful to gauge the amount of aggregation.
           The information of cluster ID and related CPUs can be gotten
           from /sys/devices/system/cpu/cpuX/topology/cluster_{id,
           cpus}.

       --per-cache
           Aggregate counts per cache instance for system-wide mode
           measurements. By default, the aggregation happens for the
           cache level at the highest index in the system. To specify a
           particular level, mention the cache level alongside the
           option in the format [Ll][1-9][0-9]*. For example: Using
           option "--per-cache=l3" or "--per-cache=L3" will aggregate
           the information at the boundary of the level 3 cache in the
           system.

       --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).

       --per-node
           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).

       -D msecs, --delay msecs
           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.

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

       --metric-no-group
           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.

       --metric-no-merge
           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.

       --metric-no-threshold
           Metric thresholds may increase the number of events necessary
           to compute whether a metric has exceeded its threshold
           expression. This may not be desirable, for example, as the
           events can introduce multiplexing. This option disables the
           adding of threshold expression events for a metric. However,
           if there are sufficient events to compute the threshold then
           the threshold is still computed and used to color the
           metric’s computed value.

       --quiet
           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         top

       Stores stat data into perf data file.

       -o file, --output file
           Output file name.

STAT REPORT         top

       Reads and reports stat data from perf data file.

       -i file, --input file
           Input file name.

       --per-socket
           Aggregate counts per processor socket for system-wide mode
           measurements.

       --per-die
           Aggregate counts per processor die for system-wide mode
           measurements.

       --per-cluster
           Aggregate counts perf processor cluster for system-wide mode
           measurements.

       --per-cache
           Aggregate counts per cache instance for system-wide mode
           measurements. By default, the aggregation happens for the
           cache level at the highest index in the system. To specify a
           particular level, mention the cache level alongside the
           option in the format [Ll][1-9][0-9]*. For example: Using
           option "--per-cache=l3" or "--per-cache=L3" will aggregate
           the information at the boundary of the level 3 cache in the
           system.

       --per-core
           Aggregate counts per physical processor for system-wide mode
           measurements.

       -M, --metrics
           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.

               When threshold information is available for a metric, the
               color red is used to signify a metric has exceeded a threshold
               while green shows it hasn't. The default color means that
               no threshold information was available or the threshold
               couldn't be computed.

       -A, --no-aggr, --no-merge
           Do not aggregate/merge counts across monitored CPUs or PMUs.

       When multiple events are created from a single event
       specification, stat will, by default, aggregate the event counts
       and show the result in a single row. This option disables that
       behavior and shows the individual events and counts.

       Multiple events are created from a single event specification
       when:

        1. PID monitoring isn’t requested and the system has more than
           one CPU. For example, a system with 8 SMT threads will have
           one event opened on each thread and aggregation is performed
           across them.

        2. Prefix or glob wildcard matching is used for the PMU name.
           For example, multiple memory controller PMUs may exist
           typically with a suffix of _0, _1, etc. By default the event
           counts will all be combined if the PMU is specified without
           the suffix such as uncore_imc rather than uncore_imc_0.

        3. Aliases, which are listed immediately after the Kernel PMU
           events by perf list, are used.

           --hybrid-merge
               Merge core event counts from all core PMUs. In hybrid or
               big.LITTLE systems by default each core PMU will report
               its count separately. This option forces core PMU counts
               to be combined to give a behavior closer to having a
               single CPU type in the system.

           --topdown
               Print 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.

       Frontend bound means that the CPU cannot fetch and decode
       instructions fast enough. Backend bound means that computation or
       memory access is the bottle neck. Bad Speculation means that the
       CPU wasted cycles due to branch mispredictions and similar
       issues. Retiring means that the CPU computed without an
       apparently bottleneck. The bottleneck is only the real bottleneck
       if the workload is actually bound by the CPU and not by something
       else.

       For best results it is usually a good idea to use it with
       interval mode like -I 1000, as the bottleneck of workloads can
       change often.

       This enables --metric-only, unless overridden with
       --no-metric-only.

       The following restrictions only apply to older Intel CPUs and
       Atom, on newer CPUs (IceLake and later) TopDown can be collected
       for any thread:

       The top down metrics are collected per core instead of per CPU
       thread. Per core mode is automatically enabled 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         top

       $ 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         top

       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         top

       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.

INTEL HYBRID SUPPORT         top

       Support for Intel hybrid events within perf tools.

       For some Intel platforms, such as AlderLake, which is hybrid
       platform and it consists of atom cpu and core cpu. Each cpu has
       dedicated event list. Part of events are available on core cpu,
       part of events are available on atom cpu and even part of events
       are available on both.

       Kernel exports two new cpu pmus via sysfs: /sys/devices/cpu_core
       /sys/devices/cpu_atom

       The cpus files are created under the directories. For example,

       cat /sys/devices/cpu_core/cpus 0-15

       cat /sys/devices/cpu_atom/cpus 16-23

       It indicates cpu0-cpu15 are core cpus and cpu16-cpu23 are atom
       cpus.

       As before, use perf-list to list the symbolic event.

       perf list

       inst_retired.any [Fixed Counter: Counts the number of
       instructions retired. Unit: cpu_atom] inst_retired.any [Number of
       instructions retired. Fixed Counter - architectural event. Unit:
       cpu_core]

       The Unit: xxx is added to brief description to indicate which pmu
       the event is belong to. Same event name but with different pmu
       can be supported.

       Enable hybrid event with a specific pmu

       To enable a core only event or atom only event, following syntax
       is supported:

                   cpu_core/<event name>/
           or
                   cpu_atom/<event name>/

       For example, count the cycles event on core cpus.

           perf stat -e cpu_core/cycles/

       Create two events for one hardware event automatically

       When creating one event and the event is available on both atom
       and core, two events are created automatically. One is for atom,
       the other is for core. Most of hardware events and cache events
       are available on both cpu_core and cpu_atom.

       For hardware events, they have pre-defined configs (e.g. 0 for
       cycles). But on hybrid platform, kernel needs to know where the
       event comes from (from atom or from core). The original perf
       event type PERF_TYPE_HARDWARE can’t carry pmu information. So now
       this type is extended to be PMU aware type. The PMU type ID is
       stored at attr.config[63:32].

       PMU type ID is retrieved from sysfs. /sys/devices/cpu_atom/type
       /sys/devices/cpu_core/type

       The new attr.config layout for PERF_TYPE_HARDWARE:

       PERF_TYPE_HARDWARE: 0xEEEEEEEE000000AA AA: hardware event ID
       EEEEEEEE: PMU type ID

       Cache event is similar. The type PERF_TYPE_HW_CACHE is extended
       to be PMU aware type. The PMU type ID is stored at
       attr.config[63:32].

       The new attr.config layout for PERF_TYPE_HW_CACHE:

       PERF_TYPE_HW_CACHE: 0xEEEEEEEE00DDCCBB BB: hardware cache ID CC:
       hardware cache op ID DD: hardware cache op result ID EEEEEEEE:
       PMU type ID

       When enabling a hardware event without specified pmu, such as,
       perf stat -e cycles -a (use system-wide in this example), two
       events are created automatically.

           ------------------------------------------------------------
           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
           ------------------------------------------------------------

       and

           ------------------------------------------------------------
           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
           ------------------------------------------------------------

       type 0 is PERF_TYPE_HARDWARE. 0x4 in 0x400000000 indicates it’s
       cpu_core pmu. 0x8 in 0x800000000 indicates it’s cpu_atom pmu
       (atom pmu type id is random).

       The kernel creates cycles (0x400000000) on cpu0-cpu15 (core
       cpus), and create cycles (0x800000000) on cpu16-cpu23 (atom
       cpus).

       For perf-stat result, it displays two events:

           Performance counter stats for 'system wide':

           6,744,979      cpu_core/cycles/
           1,965,552      cpu_atom/cycles/

       The first cycles is core event, the second cycles is atom event.

       Thread mode example:

       perf-stat reports the scaled counts for hybrid event and with a
       percentage displayed. The percentage is the event’s running
       time/enabling time.

       One example, triad_loop runs on cpu16 (atom core), while we can
       see the scaled value for core cycles is 160,444,092 and the
       percentage is 0.47%.

       perf stat -e cycles -- taskset -c 16 ./triad_loop

       As previous, two events are created.

           .ft C
           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
           .ft

       and

           .ft C
           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
           .ft

           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%)

       perf-record:

       If there is no -e specified in perf record, on hybrid platform,
       it creates two default cycles and adds them to event list. One is
       for core, the other is for atom.

       perf-stat:

       If there is no -e specified in perf stat, on hybrid platform,
       besides of software events, following events are created and
       added to event list in order.

       cpu_core/cycles/, cpu_atom/cycles/, cpu_core/instructions/,
       cpu_atom/instructions/, cpu_core/branches/, cpu_atom/branches/,
       cpu_core/branch-misses/, cpu_atom/branch-misses/

       Of course, both perf-stat and perf-record support to enable
       hybrid event with a specific pmu.

       e.g. perf stat -e cpu_core/cycles/ perf stat -e cpu_atom/cycles/
       perf stat -e cpu_core/r1a/ perf stat -e cpu_atom/L1-icache-loads/
       perf stat -e cpu_core/cycles/,cpu_atom/instructions/ perf stat -e
       {cpu_core/cycles/,cpu_core/instructions/}

       But {cpu_core/cycles/,cpu_atom/instructions/} will return warning
       and disable grouping, because the pmus in group are not matched
       (cpu_core vs. cpu_atom).

JSON FORMAT         top

       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         top

       perf-top(1), perf-list(1)

COLOPHON         top

       This page is part of the perf (Performance analysis tools for
       Linux (in Linux source tree)) project.  Information about the
       project can be found at 
       ⟨https://perf.wiki.kernel.org/index.php/Main_Page⟩.  If you have a
       bug report for this manual page, send it to
       linux-kernel@vger.kernel.org.  This page was obtained from the
       project's upstream Git repository
       ⟨http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git⟩
       on 2024-06-14.  (At that time, the date of the most recent commit
       that was found in the repository was 2024-06-13.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

perf                           2024-02-09                   PERF-STAT(1)

Pages that refer to this page: perf(1)perf-iostat(1)perf-kvm(1)perf-list(1)perf-record(1)perf-report(1)perf-top(1)