BUG? DOC: Really jiffies in /proc/schedstat?

From: Thommy Jakobsson
Date: Fri Jun 22 2018 - 11:09:30 EST


Hi,

I am measuring cpu runtime for a couple of processes, and is using
/proc/schedstat and /proc/[pid]/schedstat to do so. According to the
schedstat doc
(https://www.kernel.org/doc/Documentation/scheduler/sched-stats.txt) the last
three values are in jiffies. Doing something like

root@gvp4-base-pd-b-rev1:~# cat /proc/schedstat | grep cpu3; sleep
2; cat /proc/schedstat | grep cpu3;
cpu3 0 0 0 0 0 0 41155818663320 17173365985560 1011370906
cpu3 0 0 0 0 0 0 41157858979020 17176095339120 1011430425

on a heavy loaded system seems to suggest that at least the sum of running tasks
is in nanoseconds, not jiffies. Which I also think looks correct when
checking the
code.

For /proc/[pid]/schedstat the documentation is a bit vague on unit,
but I interpret it
to be the same as the corresponding global values. Which would mean jiffies.
Also here it looks to be in nanoseconds on my system though.

Am I just confused? is it configuration/system dependent? or is the
doc just plain
wrong?

Thanks,
Thommy Jakobsson