From: Rik van Riel <riel@redhat.com>
To: mingo@kernel.org, fransklaver@gmail.com, hpa@zytor.com,
fweisbec@gmail.com, torvalds@linux-foundation.org,
tglx@linutronix.de, wanpeng.li@hotmail.com,
linux-kernel@vger.kernel.org, garsilva@embeddedor.com,
sgruszka@redhat.com, peterz@infradead.org,
linux-tip-commits@vger.kernel.org
Subject: Re: [tip:sched/core] sched/cputime: Refactor the cputime_adjust() code
Date: Fri, 30 Jun 2017 10:00:00 -0400 [thread overview]
Message-ID: <1498831200.6130.13.camel@redhat.com> (raw)
In-Reply-To: <tip-72298e5c92c50edd8cb7cfda4519483ce65fa166@git.kernel.org>
On Fri, 2017-06-30 at 06:10 -0700, tip-bot for Gustavo A. R. Silva
wrote:
> +++ b/kernel/sched/cputime.c
> @@ -615,19 +615,13 @@ static void cputime_adjust(struct task_cputime
> *curr,
> * userspace. Once a task gets some ticks, the monotonicy
> code at
> * 'update' will ensure things converge to the observed
> ratio.
> */
> - if (stime == 0) {
> - utime = rtime;
> - goto update;
> + if (stime != 0) {
> + if (utime == 0)
> + stime = rtime;
> + else
> + stime = scale_stime(stime, rtime, stime +
> utime);
> }
>
> - if (utime == 0) {
> - stime = rtime;
> - goto update;
> - }
> -
> - stime = scale_stime(stime, rtime, stime + utime);
> -
> -update:
Wait, what?
This get rid of the utime = rtime assignment, when
stime == 0. That could be a correctness issue.
> /*
> * Make sure stime doesn't go backwards; this preserves
> monotonicity
> * for utime because rtime is monotonic.
next prev parent reply other threads:[~2017-06-30 14:00 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-27 23:03 [kernel-sched-cputime] question about probable bug in cputime_adjust() Gustavo A. R. Silva
2017-06-28 5:35 ` Frans Klaver
2017-06-28 6:03 ` Frans Klaver
2017-06-28 23:57 ` Gustavo A. R. Silva
2017-06-29 4:51 ` Frans Klaver
2017-06-29 17:58 ` Gustavo A. R. Silva
2017-06-29 18:41 ` [PATCH] sched/cputime: code refactoring " Gustavo A. R. Silva
2017-06-30 13:10 ` [tip:sched/core] sched/cputime: Refactor the cputime_adjust() code tip-bot for Gustavo A. R. Silva
2017-06-30 14:00 ` Rik van Riel [this message]
2017-06-30 14:41 ` Frans Klaver
2017-06-30 15:46 ` Frederic Weisbecker
2017-06-30 16:17 ` Stanislaw Gruszka
2017-07-04 9:17 ` Peter Zijlstra
2017-07-04 10:01 ` Ingo Molnar
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