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docs/scheduler: fix unit error 

The unit mentioned in the documentation of scheduler statistics is
outdated which may mislead the readers.

The unit of statistics that is reported by /proc/schedstat is modified
to nanosecond, and the unit of statistics that is reported by
/proc/PID/schedstat is provided as well to make the context consistent.

The rq_cpu_time and the rq_sched_info.run_delay of a run queue, and the
sched_info.run_delay of a task are all updated based on the clock of the
run queue, while the se.sum_exec_runtime of a task is updated based on
the clock_task of the run queue of the task. Both the clock and
clock_task are relied on the return value of the function sched_clock()
which is in the unit of nanosecond.

Signed-off-by: Jui-Tse Huang <juitse.huang@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Jui-Tse Huang 2022-04-15 11:36:18 +08:00 committed by Jonathan Corbet
parent 389cfd9670
commit 6c757e9f55
1 changed files with 2 additions and 2 deletions
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4
Documentation/scheduler/sched-stats.rst
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@ -155,8 +155,8 @@ schedstats also adds a new /proc/<pid>/schedstat file to include some of
the same information on a per-process level. There are three fields in
this file correlating for that process to:
1) time spent on the cpu
2) time spent waiting on a runqueue
1) time spent on the cpu (in nanoseconds)
2) time spent waiting on a runqueue (in nanoseconds)
3) # of timeslices run on this cpu
A program could be easily written to make use of these extra fields to