1PERF-KOWRK(1)                     perf Manual                    PERF-KOWRK(1)
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NAME

6       perf-kwork - Tool to trace/measure kernel work properties (latencies)
7

SYNOPSIS

DESCRIPTION

10       There are several variants of perf kwork:
11
12           'perf kwork record <command>' to record the kernel work
13           of an arbitrary workload.
14
15           'perf kwork report' to report the per kwork runtime.
16
17           'perf kwork latency' to report the per kwork latencies.
18
19           'perf kwork timehist' provides an analysis of kernel work events.
20
21           Example usage:
22               perf kwork record -- sleep 1
23               perf kwork report
24               perf kwork report -b
25               perf kwork latency
26               perf kwork latency -b
27               perf kwork timehist
28
29           By default it shows the individual work events such as irq, workqeueu,
30           including the run time and delay (time between raise and actually entry):
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32              Runtime start      Runtime end        Cpu     Kwork name                 Runtime     Delaytime
33                                                            (TYPE)NAME:NUM             (msec)      (msec)
34           -----------------  -----------------  ------  -------------------------  ----------  ----------
35              1811186.976062     1811186.976327  [0000]  (s)RCU:9                        0.266       0.114
36              1811186.978452     1811186.978547  [0000]  (s)SCHED:7                      0.095       0.171
37              1811186.980327     1811186.980490  [0000]  (s)SCHED:7                      0.162       0.083
38              1811186.981221     1811186.981271  [0000]  (s)SCHED:7                      0.050       0.077
39              1811186.984267     1811186.984318  [0000]  (s)SCHED:7                      0.051       0.075
40              1811186.987252     1811186.987315  [0000]  (s)SCHED:7                      0.063       0.081
41              1811186.987785     1811186.987843  [0006]  (s)RCU:9                        0.058       0.645
42              1811186.988319     1811186.988383  [0000]  (s)SCHED:7                      0.064       0.143
43              1811186.989404     1811186.989607  [0002]  (s)TIMER:1                      0.203       0.111
44              1811186.989660     1811186.989732  [0002]  (s)SCHED:7                      0.072       0.310
45              1811186.991295     1811186.991407  [0002]  eth0:10                         0.112
46              1811186.991639     1811186.991734  [0002]  (s)NET_RX:3                     0.095       0.277
47              1811186.989860     1811186.991826  [0002]  (w)vmstat_shepherd              1.966       0.345
48            ...
49
50           Times are in msec.usec.
51

OPTIONS

53       -D, --dump-raw-trace=
54           Display verbose dump of the sched data.
55
56       -f, --force
57           Don’t complain, do it.
58
59       -k, --kwork
60           List of kwork to profile (irq, softirq, workqueue, etc)
61
62       -v, --verbose
63           Be more verbose. (show symbol address, etc)
64
65       OPTIONS for perf kwork report
66
67
68           .ft C
69           -b::
70           --use-bpf::
71                   Use BPF to measure kwork runtime
72
73           -C::
74           --cpu::
75                   Only show events for the given CPU(s) (comma separated list).
76
77           -i::
78           --input::
79                   Input file name. (default: perf.data unless stdin is a fifo)
80
81           -n::
82           --name::
83                   Only show events for the given name.
84
85           -s::
86           --sort::
87                   Sort by key(s): runtime, max, count
88
89           -S::
90           --with-summary::
91                   Show summary with statistics
92
93           --time::
94                   Only analyze samples within given time window: <start>,<stop>. Times
95                   have the format seconds.microseconds. If start is not given (i.e., time
96                   string is ',x.y') then analysis starts at the beginning of the file. If
97                   stop time is not given (i.e, time string is 'x.y,') then analysis goes
98                   to end of file.
99
100           OPTIONS for 'perf kwork latency'
101           .ft
102
103
104       -b, --use-bpf
105           Use BPF to measure kwork latency
106
107       -C, --cpu
108           Only show events for the given CPU(s) (comma separated list).
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110       -i, --input
111           Input file name. (default: perf.data unless stdin is a fifo)
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113       -n, --name
114           Only show events for the given name.
115
116       -s, --sort
117           Sort by key(s): avg, max, count
118
119       --time
120           Only analyze samples within given time window: <start>,<stop>.
121           Times have the format seconds.microseconds. If start is not given
122           (i.e., time string is ,x.y) then analysis starts at the beginning
123           of the file. If stop time is not given (i.e, time string is x.y,)
124           then analysis goes to end of file.
125

OPTIONS FOR PERF KWORK TIMEHIST

127       -C, --cpu
128           Only show events for the given CPU(s) (comma separated list).
129
130       -g, --call-graph
131           Display call chains if present (default off).
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133       -i, --input
134           Input file name. (default: perf.data unless stdin is a fifo)
135
136       -k, --vmlinux=<file>
137           Vmlinux pathname
138
139       -n, --name
140           Only show events for the given name.
141
142       --kallsyms=<file>
143           Kallsyms pathname
144
145       --max-stack
146           Maximum number of functions to display in backtrace, default 5.
147
148       --symfs=<directory>
149           Look for files with symbols relative to this directory.
150
151       --time
152           Only analyze samples within given time window: <start>,<stop>.
153           Times have the format seconds.microseconds. If start is not given
154           (i.e., time string is ,x.y) then analysis starts at the beginning
155           of the file. If stop time is not given (i.e, time string is x.y,)
156           then analysis goes to end of file.
157

SEE ALSO

159       perf-record(1)
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163perf                              01/12/2023                     PERF-KOWRK(1)
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