PERF-SCHED(1) | perf Manual | PERF-SCHED(1) |
perf-sched - Tool to trace/measure scheduler properties (latencies)
perf sched {record|latency|map|replay|script|timehist}
There are several variants of perf sched:
'perf sched record <command>' to record the scheduling events of an arbitrary workload.
'perf sched latency' to report the per task scheduling latencies and other scheduling properties of the workload.
'perf sched script' to see a detailed trace of the workload that
was recorded (aliased to 'perf script' for now).
'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.)
'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.
'perf sched timehist' provides an analysis of scheduling events.
Example usage:
perf sched record -- sleep 1
perf sched timehist
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:
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.
-i, --input=<file>
-v, --verbose
-D, --dump-raw-trace=
-f, --force
--compact
--cpus
--color-cpus
--color-pids
-k, --vmlinux=<file>
--kallsyms=<file>
-g, --call-graph
--max-stack
-C=, --cpu=
-p=, --pid=
-t=, --tid=
-s, --summary
-S, --with-summary
--symfs=<directory>
-V, --cpu-visual
-w, --wakeups
-M, --migrations
-n, --next
-I, --idle-hist
--time
--state
2024-02-01 | perf |