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PERF-KWORK(1)   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

-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'

-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.

OPTIONS for perf kwork top

-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
--------
linkperf:perf-record[1]