Re: /proc/pid/sched units

["Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>]

Hello Shivank,

On Wed, 28 Jul 2021 at 14:59, Shivank Garg <shivankgarg98@gmail.com> wrote:
>
> ---------- Forwarded message ---------
> From: Shivank Garg <shivankgarg98@gmail.com>
> Date: Wed, Jul 28, 2021 at 6:26 PM
> Subject: /proc/pid/sched units
> To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Linux MM
> <linux-mm@kvack.org>, <util-linux@vger.kernel.org>
>
>
> Hi Everyone,
>
> I'm analyzing the cpu time taken ("se.sum_exec_runtime" in
> /proc/$pid/sched) by process in different configurations for my
> project work. But I was not able to get the time units for the values
> displayed in the file. I tried searching it in source code -
> kernel/sched/cputime.c,include/linux/sched.h etc. but it left me more
> confused.
>
> Can you please answer me about the measurement units (is it
> microseconds, nanoseconds, jiffles ...) ?
>
> Also, I was not able to find proper documentation for /proc/pid/sched.
> Please point to me if it's already there. If not, I would love to
> contribute toward documenting these variables. It would be very
> helpful for newbies (like me) in future.

It looks like se.sum_exec_runtime is milliseconds. In
kernel/sched/debug.c, see proc_sched_show_task(), the definition of
the PN() PNS(), and SPLIT_NS() macros, and the nsec_high(x) and
nsec_low(x) functions.

Thanks,

Michael


--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/