From: Stanislaw Gruszka <sgruszka@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Christian Engelmayer <cengelma@gmx.at>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
fweisbec@gmail.com, Paul Turner <pjt@google.com>
Subject: Re: [PROBLEM] possible divide by 0 in kernel/sched/cputime.c scale_stime()
Date: Wed, 20 Nov 2013 13:08:25 +0100 [thread overview]
Message-ID: <20131120120815.GA12860@redhat.com> (raw)
In-Reply-To: <20131118172706.GI3866@twins.programming.kicks-ass.net>
On Mon, Nov 18, 2013 at 06:27:06PM +0100, Peter Zijlstra wrote:
> The below is a compile tested only attempt to deal with both these
> problems. Comments?
Just two nits as I don't understand vast of the patch.
> + delta_exec = now - curr->exec_start;
> + if ((s64)delta_exec < 0)
> return;
Check here should probably use <= and also unlikely() would be
reasonable.
> + schedstat_set(curr->statistics.exec_max,
> + max((u64)delta_exec, curr->statistics.exec_max));
(u64) cast not needed.
Stanislaw
next prev parent reply other threads:[~2013-11-20 11:11 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-16 21:37 [PROBLEM] possible divide by 0 in kernel/sched/cputime.c scale_stime() Christian Engelmayer
2013-11-18 14:02 ` Stanislaw Gruszka
2013-11-18 14:19 ` Peter Zijlstra
2013-11-18 15:39 ` Ingo Molnar
2013-11-18 17:27 ` Peter Zijlstra
2013-11-20 12:08 ` Stanislaw Gruszka [this message]
2013-11-25 0:43 ` Christian Engelmayer
2013-11-26 14:44 ` [PATCH] sched, fair: Rework sched_fair time accounting Peter Zijlstra
2013-12-12 9:52 ` [tip:sched/urgent] sched/fair: " tip-bot for Peter Zijlstra
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