From: Rik van Riel <riel@redhat.com>
To: Frederic Weisbecker <fweisbec@gmail.com>, Ingo Molnar <mingo@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Wanpeng Li <wanpeng.li@hotmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Stanislaw Gruszka <sgruszka@redhat.com>
Subject: Re: [PATCH] sched/cputime: Fix ksoftirqd cputime accounting regression
Date: Wed, 26 Apr 2017 11:44:04 -0400 [thread overview]
Message-ID: <1493221444.31102.3.camel@redhat.com> (raw)
In-Reply-To: <1493129448-5356-1-git-send-email-fweisbec@gmail.com>
On Tue, 2017-04-25 at 16:10 +0200, Frederic Weisbecker wrote:
> irq_time_read() returns the irqtime minus the ksoftirqd time. This
> is necessary because irq_time_read() is used to substract the IRQ
> time
> from the sum_exec_runtime of a task. If we were to include the
> softirq
> time of ksoftirqd, this task would substract its own CPU time
> everytime
> it updates ksoftirqd->sum_exec_runtime which would therefore never
> progress.
>
> But this behaviour got broken by commit a499a5a14db:
> ("sched/cputime: Increment kcpustat directly on irqtime
> account")
> which now includes ksoftirqd softirq time in the time returned by
> irq_time_read().
Ahhh, after a look at account_system_time, it becomes
clear why that was happening!
Reviewed-by: Rik van Riel <riel@redhat.com>
next prev parent reply other threads:[~2017-04-26 15:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-25 14:10 [PATCH] sched/cputime: Fix ksoftirqd cputime accounting regression Frederic Weisbecker
2017-04-26 14:30 ` Jesper Dangaard Brouer
2017-04-26 15:44 ` Rik van Riel [this message]
2017-04-27 14:16 ` [tip:sched/urgent] " tip-bot for Frederic Weisbecker
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