# perf-kwork

## 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>
               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)
    


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