perf-sched (1)
Leading comments
Title: perf-sched
Author: [FIXME: author] [see http://docbook.sf.net/el/author]
Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
Date: 09/12/2017
Manual: perf Manual
Source: perf
Language: English
NAME
perf-sched - Tool to trace/measure scheduler properties (latencies)SYNOPSIS
perf sched {record|latency|map|replay|script|timehist}
DESCRIPTION
There are several variants of perf sched:
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'perf sched record <command>' to record the scheduling events of an arbitrary workload.
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'perf sched latency' to report the per task scheduling latencies and other scheduling properties of the workload.
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'perf sched script' to see a detailed trace of the workload that was recorded (aliased to 'perf script' for now).
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'perf sched replay' to simulate the workload that was recorded via perf sched record. (this is done by starting up mockup threads that mimic the workload based on the events in the trace. These threads can then replay the timings (CPU runtime and sleep patterns) of the workload as it occurred when it was recorded - and can repeat it a number of times, measuring its performance.)
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'perf sched map' to print a textual context-switching outline of workload captured via perf sched record. Columns stand for individual CPUs, and the two-letter shortcuts stand for tasks that are running on a CPU. A '*' denotes the CPU that had the event, and 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: perf sched record -- sleep 1 perf sched timehist
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By default it shows the individual schedule events, including the wait time (time between sched-out and next sched-in events for the task), the task scheduling delay (time between wakeup and actually running) and run time for the task:
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time cpu task name wait time sch delay run time [tid/pid] (msec) (msec) (msec) -------------- ------ -------------------- --------- --------- --------- 79371.874569 [0011] gcc[31949] 0.014 0.000 1.148 79371.874591 [0010] gcc[31951] 0.000 0.000 0.024 79371.874603 [0010] migration/10[59] 3.350 0.004 0.011 79371.874604 [0011] <idle> 1.148 0.000 0.035 79371.874723 [0005] <idle> 0.016 0.000 1.383 79371.874746 [0005] gcc[31949] 0.153 0.078 0.022 ...
-
Times are in msec.usec.
OPTIONS
-i, --input=<file>
- Input file name. (default: perf.data unless stdin is a fifo)
-v, --verbose
- Be more verbose. (show symbol address, etc)
-D, --dump-raw-trace=
- Display verbose dump of the sched data.
OPTIONS FOR FIPERF SCHED MAPFR
--compact
- Show only CPUs with activity. Helps visualizing on high core count systems.
--cpus
- Show just entries with activities for the given CPUs.
--color-cpus
- Highlight the given cpus.
--color-pids
- Highlight the given pids.
OPTIONS FOR FIPERF SCHED TIMEHISTFR
-k, --vmlinux=<file>
- vmlinux pathname
--kallsyms=<file>
- kallsyms pathname
-g, --no-call-graph
- Do not display call chains if present.
--max-stack
- Maximum number of functions to display in backtrace, default 5.
-s, --summary
- Show only a summary of scheduling by thread with min, max, and average run times (in sec) and relative stddev.
-S, --with-summary
- Show all scheduling events followed by a summary by thread with min, max, and average run times (in sec) and relative stddev.
--symfs=<directory>
- Look for files with symbols relative to this directory.
-V, --cpu-visual
- Show visual aid for sched switches by CPU: i marks idle time, s are scheduler events.
-w, --wakeups
- Show wakeup events.
-M, --migrations
- Show migration events.
-n, --next
- Show next task.
-I, --idle-hist
- Show idle-related events only.
--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.
--state
- Show task state when it switched out.