Re: [PATCH] oom_kill: fix calculation of the cpu_time and the run_time

From: KOSAKI Motohiro
Date: Tue Oct 07 2008 - 07:16:01 EST


> Hi all
>
> The cpu-time is in tens of seconds
> and the run-time is in thousands of secounds.
>
> but the source code doesn't follow it.

Have you seen any trouble?

>
> I fixed it and also some white-spaces.
> Could you please check this patch.
>
>
> Signed-off-by: Naohiro Ooiwa <nooiwa@xxxxxxxxxxxxxxxx>
> ---
> mm/oom_kill.c | 10 +++++-----
> 1 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 64e5b4b..bddab74 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -100,14 +100,14 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
>
> /*
> * CPU time is in tens of seconds and run time is in thousands
> - * of seconds. There is no particular reason for this other than
> - * that it turned out to work very well in practice.
> + * of seconds. There is no particular reason for this other than
> + * that it turned out to work very well in practice.
> */
> - cpu_time = (cputime_to_jiffies(p->utime) + cputime_to_jiffies(p->stime))
> - >> (SHIFT_HZ + 3);
> + cpu_time = ((cputime_to_jiffies(p->utime) + cputime_to_jiffies(p->stime))
> + >> SHIFT_HZ) / 10UL;
>
> if (uptime >= p->start_time.tv_sec)
> - run_time = (uptime - p->start_time.tv_sec) >> 10;
> + run_time = (uptime - p->start_time.tv_sec) / 1000UL;
> else
> run_time = 0;

in some architecture, shift-op outperfom divide-op largely.
why do you need this change?



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