Revision as of 14:35, 14 March 2024

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, 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, 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 FIPERF KWORK TIMEHISTFR

-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

.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)

KERNEL VERSION

This page is auto-generated. The kernel version is v6.8