PERF-KWORK(1)

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

SYNOPSIS

perf kwork {record|report|latency|timehist|top}

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.

    'perf kwork top' to report the task cpu usage.

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

    By default it shows the individual work events such as irq, workqueue,
    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, sched, 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[,layout]>
    Look for files with symbols relative to this directory. The optional layout can be hierarchy (default, matches full path) or flat (only matches base name). This is useful when debug files are stored in a flat directory structure.

--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 top

    .ft C
    -b::
    --use-bpf::
            Use BPF to measure task cpu usage.
    -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): rate, runtime, tid
    --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
    .ft

perf-record(1)