NAME

       perf-kwork - Tool to trace/measure kernel work properties (latencies)

SYNOPSIS

       perf kwork {record|report|latency|timehist}

DESCRIPTION

       There are several variants of perf kwork:

           'perf kwork record <command>' to record the kernel work
           of an arbitrary workload.

           'perf kwork report' to report the per kwork runtime.

           'perf kwork latency' to report the per kwork latencies.

           'perf kwork timehist' provides an analysis of kernel work events.

           Example usage:
               perf kwork record -- sleep 1
               perf kwork report
               perf kwork report -b
               perf kwork latency
               perf kwork latency -b
               perf kwork timehist

           By default it shows the individual work events such as irq, workqeueu,
           including the run time and delay (time between raise and actually entry):

              Runtime start      Runtime end        Cpu     Kwork name                 Runtime     Delaytime
                                                            (TYPE)NAME:NUM             (msec)      (msec)
           -----------------  -----------------  ------  -------------------------  ----------  ----------
              1811186.976062     1811186.976327  [0000]  (s)RCU:9                        0.266       0.114
              1811186.978452     1811186.978547  [0000]  (s)SCHED:7                      0.095       0.171
              1811186.980327     1811186.980490  [0000]  (s)SCHED:7                      0.162       0.083
              1811186.981221     1811186.981271  [0000]  (s)SCHED:7                      0.050       0.077
              1811186.984267     1811186.984318  [0000]  (s)SCHED:7                      0.051       0.075
              1811186.987252     1811186.987315  [0000]  (s)SCHED:7                      0.063       0.081
              1811186.987785     1811186.987843  [0006]  (s)RCU:9                        0.058       0.645
              1811186.988319     1811186.988383  [0000]  (s)SCHED:7                      0.064       0.143
              1811186.989404     1811186.989607  [0002]  (s)TIMER:1                      0.203       0.111
              1811186.989660     1811186.989732  [0002]  (s)SCHED:7                      0.072       0.310
              1811186.991295     1811186.991407  [0002]  eth0:10                         0.112
              1811186.991639     1811186.991734  [0002]  (s)NET_RX:3                     0.095       0.277
              1811186.989860     1811186.991826  [0002]  (w)vmstat_shepherd              1.966       0.345
            ...

           Times are in msec.usec.

OPTIONS

       -D, --dump-raw-trace=
           Display verbose dump of the sched data.

       -f, --force
           Don’t complain, do it.

       -k, --kwork
           List of kwork to profile (irq, softirq, workqueue, etc)

       -v, --verbose
           Be more verbose. (show symbol address, etc)

       OPTIONS for perf kwork report

           .ft C
           -b::
           --use-bpf::
                   Use BPF to measure kwork runtime

           -C::
           --cpu::
                   Only show events for the given CPU(s) (comma separated list).

           -i::
           --input::
                   Input file name. (default: perf.data unless stdin is a fifo)

           -n::
           --name::
                   Only show events for the given name.

           -s::
           --sort::
                   Sort by key(s): runtime, max, count

           -S::
           --with-summary::
                   Show summary with statistics

           --time::
                   Only analyze samples within given time window: <start>,<stop>. Times
                   have the format seconds.microseconds. If start is not given (i.e., time
                   string is ',x.y') then analysis starts at the beginning of the file. If
                   stop time is not given (i.e, time string is 'x.y,') then analysis goes
                   to end of file.

           OPTIONS for 'perf kwork latency'
           .ft

       -b, --use-bpf
           Use BPF to measure kwork latency

       -C, --cpu
           Only show events for the given CPU(s) (comma separated list).

       -i, --input
           Input file name. (default: perf.data unless stdin is a fifo)

       -n, --name
           Only show events for the given name.

       -s, --sort
           Sort by key(s): avg, max, count

       --time
           Only analyze samples within given time window: <start>,<stop>. Times have the format
           seconds.microseconds. If start is not given (i.e., time string is ,x.y) then analysis
           starts at the beginning of the file. If stop time is not given (i.e, time string is
           x.y,) then analysis goes to end of file.

OPTIONS FOR PERF KWORK TIMEHIST

       -C, --cpu
           Only show events for the given CPU(s) (comma separated list).

       -g, --call-graph
           Display call chains if present (default off).

       -i, --input
           Input file name. (default: perf.data unless stdin is a fifo)

       -k, --vmlinux=<file>
           Vmlinux pathname

       -n, --name
           Only show events for the given name.

       --kallsyms=<file>
           Kallsyms pathname

       --max-stack
           Maximum number of functions to display in backtrace, default 5.

       --symfs=<directory>
           Look for files with symbols relative to this directory.

       --time
           Only analyze samples within given time window: <start>,<stop>. Times have the format
           seconds.microseconds. If start is not given (i.e., time string is ,x.y) then analysis
           starts at the beginning of the file. If stop time is not given (i.e, time string is
           x.y,) then analysis goes to end of file.

SEE ALSO

       perf-record(1)