Manual: perf-kwork

PERF-KWORK(1)						 perf Manual					       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 ' 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: ,. 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: ,. 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=
	   Vmlinux pathname

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

       --kallsyms=
	   Kallsyms pathname

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

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

       --time
	   Only analyze samples within given time window: ,. 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: ,. 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)

perf							 07/31/2026					       PERF-KWORK(1)