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Date: Wed, 21 May 2014 08:38:26 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Jason Low <jason.low2@hp.com>, Ingo Molnar <mingo@elte.hu>,
        Andrew Morton <akpm@linux-foundation.org>,
        Len Brown <len.brown@intel.com>, Russ Anderson <rja@sgi.com>,
        Dimitri Sivanich <sivanich@sgi.com>, Hedi Berriche <hedi@sgi.com>,
        Andi Kleen <andi@firstfloor.org>,
        Michel Lespinasse <walken@google.com>, Rik van Riel <riel@redhat.com>,
        Peter Hurley <peter@hurleysoftware.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] sched: Reduce the rate of needless idle load balancing
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On Tue, May 20, 2014 at 02:39:27PM -0700, Tim Chen wrote:
> From: Tim Chen <tim.c.chen@linux.intel.com>
> Subject: [PATCH v2] sched: Reduce the rate of needless idle load balancing
>=20
>=20
> The current no_hz idle load balancer do load balancing for *all* idle cpu=
s,
> even though the time due to load balance for a particular
> idle cpu could be still a while in the future.  This introduces a much
> higher load balancing rate than what is necessary.  The patch
> changes the behavior by only doing idle load balancing on
> behalf of an idle cpu only when it is due for load balancing.
>=20
> On SGI's systems with over 3000 cores, the cpu responsible for idle balan=
cing
> got overwhelmed with idle balancing, and introduces a lot of OS noise
> to workloads.  This patch fixes the issue.
>=20
> Acked-by: Russ Anderson <rja@sgi.com>
> Reviewed-by: Rik van Riel <riel@redhat.com>
> Reviewed-by: Jason Low <jason.low2@hp.com>
> Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
> ---

Thanks!

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