perf-sched(1)
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=============
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NAME
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----
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perf-sched - Tool to trace/measure scheduler properties (latencies)
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SYNOPSIS
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--------
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[verse]
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'perf sched' {record|latency|map|replay|script|timehist}
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DESCRIPTION
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-----------
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There are several variants of 'perf sched':
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'perf sched record <command>' to record the scheduling events
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of an arbitrary workload.
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'perf sched latency' to report the per task scheduling latencies
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and other scheduling properties of the workload.
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'perf sched script' to see a detailed trace of the workload that
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was recorded (aliased to 'perf script' for now).
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'perf sched replay' to simulate the workload that was recorded
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via perf sched record. (this is done by starting up mockup threads
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that mimic the workload based on the events in the trace. These
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threads can then replay the timings (CPU runtime and sleep patterns)
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of the workload as it occurred when it was recorded - and can repeat
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it a number of times, measuring its performance.)
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'perf sched map' to print a textual context-switching outline of
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workload captured via perf sched record. Columns stand for
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individual CPUs, and the two-letter shortcuts stand for tasks that
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are running on a CPU. A '*' denotes the CPU that had the event, and
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a dot signals an idle CPU.
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'perf sched timehist' provides an analysis of scheduling events.
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Example usage:
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perf sched record -- sleep 1
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perf sched timehist
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By default it shows the individual schedule events, including the wait
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time (time between sched-out and next sched-in events for the task), the
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task scheduling delay (time between wakeup and actually running) and run
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time for the task:
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time cpu task name wait time sch delay run time
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[tid/pid] (msec) (msec) (msec)
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-------------- ------ -------------------- --------- --------- ---------
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79371.874569 [0011] gcc[31949] 0.014 0.000 1.148
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79371.874591 [0010] gcc[31951] 0.000 0.000 0.024
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79371.874603 [0010] migration/10[59] 3.350 0.004 0.011
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79371.874604 [0011] <idle> 1.148 0.000 0.035
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79371.874723 [0005] <idle> 0.016 0.000 1.383
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79371.874746 [0005] gcc[31949] 0.153 0.078 0.022
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...
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Times are in msec.usec.
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OPTIONS
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-------
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-i::
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--input=<file>::
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Input file name. (default: perf.data unless stdin is a fifo)
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-v::
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--verbose::
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Be more verbose. (show symbol address, etc)
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-D::
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--dump-raw-trace=::
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Display verbose dump of the sched data.
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-f::
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--force::
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Don't complain, do it.
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OPTIONS for 'perf sched map'
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----------------------------
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--compact::
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Show only CPUs with activity. Helps visualizing on high core
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count systems.
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--cpus::
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Show just entries with activities for the given CPUs.
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--color-cpus::
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Highlight the given cpus.
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--color-pids::
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Highlight the given pids.
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OPTIONS for 'perf sched timehist'
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---------------------------------
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-k::
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--vmlinux=<file>::
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vmlinux pathname
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--kallsyms=<file>::
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kallsyms pathname
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-g::
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--call-graph::
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Display call chains if present (default on).
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--max-stack::
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Maximum number of functions to display in backtrace, default 5.
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-C=::
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--cpu=::
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Only show events for the given CPU(s) (comma separated list).
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-p=::
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--pid=::
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Only show events for given process ID (comma separated list).
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-t=::
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--tid=::
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Only show events for given thread ID (comma separated list).
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-s::
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--summary::
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Show only a summary of scheduling by thread with min, max, and average
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run times (in sec) and relative stddev.
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-S::
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--with-summary::
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Show all scheduling events followed by a summary by thread with min,
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max, and average run times (in sec) and relative stddev.
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--symfs=<directory>::
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Look for files with symbols relative to this directory.
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-V::
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--cpu-visual::
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Show visual aid for sched switches by CPU: 'i' marks idle time,
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's' are scheduler events.
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-w::
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--wakeups::
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Show wakeup events.
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-M::
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--migrations::
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Show migration events.
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-n::
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--next::
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Show next task.
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-I::
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--idle-hist::
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Show idle-related events only.
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--time::
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Only analyze samples within given time window: <start>,<stop>. Times
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have the format seconds.microseconds. If start is not given (i.e., time
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string is ',x.y') then analysis starts at the beginning of the file. If
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stop time is not given (i.e, time string is 'x.y,') then analysis goes
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to end of file.
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--state::
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Show task state when it switched out.
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SEE ALSO
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--------
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linkperf:perf-record[1]
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