From: Peter Zijlstra <peterz@infradead.org>
To: Chase Douglas <chase.douglas@canonical.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
"Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: [REGRESSION 2.6.30][PATCH 1/1] sched: defer idle accounting till after load update period
Date: Mon, 29 Mar 2010 16:41:58 +0200 [thread overview]
Message-ID: <1269873718.12097.342.camel@laptop> (raw)
In-Reply-To: <1269870072-22449-2-git-send-email-chase.douglas@canonical.com>
On Mon, 2010-03-29 at 09:41 -0400, Chase Douglas wrote:
> There's a period of 10 ticks where calc_load_tasks is updated by all the
> cpus for the load avg. Usually all the cpus do this during the first
> tick. If any cpus go idle, calc_load_tasks is decremented accordingly.
> However, if they wake up calc_load_tasks is not incremented. Thus, if
> cpus go idle during the 10 tick period, calc_load_tasks may be
> decremented to a non-representative value. This issue can lead to
> systems having a load avg of exactly 0, even though the real load avg
> could theoretically be up to NR_CPUS.
>
> This change defers calc_load_tasks accounting after each cpu updates the
> count until after the 10 tick period.
>From reading the above changelog it seems to me there should be a
callback from leaving nohz mode, your proposed patch has no such thing.
next prev parent reply other threads:[~2010-03-29 14:42 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-29 13:41 [REGRESSION 2.6.30][PATCH 0/1] sched: defer idle accounting till after load update period Chase Douglas
2010-03-29 13:41 ` [REGRESSION 2.6.30][PATCH 1/1] " Chase Douglas
2010-03-29 14:41 ` Peter Zijlstra [this message]
2010-03-29 17:20 ` Chase Douglas
2010-04-01 19:27 ` Andrew Morton
2010-04-01 19:37 ` Thomas Gleixner
2010-04-01 20:00 ` Chase Douglas
2010-04-01 20:18 ` Thomas Gleixner
2010-04-01 20:32 ` Chase Douglas
2010-04-01 20:37 ` Thomas Gleixner
2010-04-02 7:59 ` Peter Zijlstra
2010-04-05 14:44 ` Chase Douglas
2010-04-01 19:56 ` Chase Douglas
2010-04-01 20:01 ` Thomas Gleixner
2010-04-13 20:39 ` Andrew Morton
2010-04-13 21:02 ` Thomas Gleixner
2010-04-13 21:06 ` Chase Douglas
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