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From: Vincent Guittot <vincent.guittot@linaro.org>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Youquan Song <youquan.song@intel.com>,
	linux-kernel@vger.kernel.org, mingo@elte.hu, tglx@linutronix.de,
	hpa@zytor.com, akpm@linux-foundation.org, stable@vger.kernel.org,
	arjan@linux.intel.com, len.brown@intel.com, anhua.xu@intel.com,
	chaohong.guo@intel.com,
	Youquan Song <youquan.song@linux.intel.com>
Subject: Re: [PATCH] x86,sched: Fix sched_smt_power_savings totally broken
Date: Tue, 10 Jan 2012 09:08:06 +0100	[thread overview]
Message-ID: <CAKfTPtA_ORWsgLOZ2+Nn8RdAXQ_4Nu16RCk9J3f04+YyjYuemA@mail.gmail.com> (raw)
In-Reply-To: <1326160461.2366.19.camel@sbsiddha-mobl2>

On 10 January 2012 02:54, Suresh Siddha <suresh.b.siddha@intel.com> wrote:
> On Mon, 2012-01-09 at 15:29 +0100, Vincent Guittot wrote:
>> Hi Peter,
>>
>> I'm also using sched_mc level for doing powersaving load balance on
>> ARM platform and we have real benefits.
>
> hi Vincent, Can you elaborate on your platform topology where you see
> the benefits?
>

Hi Suresh,

I'm using dual/quad cores ARM platform. When sched_mc is different
from 0, the topology is changed from 1 socket/cluster to 2 virtual
sockets/clusters with 1 or 2 cores in each cluster.  For low cpu load
situation, the tasks are gathered in 1 virtual socket and let the
cores in the other socket to enter idle state thanks to cpuidle. On
ARM platform, cores in a cluster can enter interesting idle state even
if the complete cluster can't reach a deep idle state.
With dual cores platform, i'm increasing the cpu_power to gather tasks
on 1 core when cores are at lowest frequency. In fact i'm detecting a
low cpu load (only small tasks are running) and ensure that these
small tasks are kept on 1 core.

Regards,
Vincent

> on x86, 'sched_mc' was designed for the case of consolidating load into
> one socket before using another idle socket.
>
> Just wondering if this is your use case too or if you are consolidating
> at a different topological level.
>
> thanks,
> suresh
>

  reply	other threads:[~2012-01-10  8:08 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-09  8:56 [PATCH] x86,sched: Fix sched_smt_power_savings totally broken Youquan Song
2012-01-09 10:06 ` Peter Zijlstra
2012-01-09 10:28   ` Peter Zijlstra
2012-01-09 10:30     ` Peter Zijlstra
2012-01-09 11:00     ` Vaidyanathan Srinivasan
2012-01-09 14:35       ` Peter Zijlstra
2012-01-09 16:03         ` Vaidyanathan Srinivasan
2012-01-09 16:13           ` Peter Zijlstra
2012-01-09 17:05             ` Vaidyanathan Srinivasan
2012-01-09 14:13     ` Arjan van de Ven
2012-05-18 10:19     ` [tip:sched/core] sched: Remove stale power aware scheduling remnants and dysfunctional knobs tip-bot for Peter Zijlstra
2012-01-10  0:14   ` [PATCH] x86,sched: Fix sched_smt_power_savings totally broken Youquan Song
2012-01-09 11:05     ` Peter Zijlstra
2012-01-10  5:58       ` Youquan Song
2012-01-09 23:52         ` Suresh Siddha
2012-01-10  9:18           ` Ingo Molnar
2012-01-10 14:32             ` Arjan van de Ven
2012-01-10 14:41               ` Peter Zijlstra
2012-01-10 14:54                 ` Arjan van de Ven
2012-01-10 15:32               ` Vincent Guittot
2012-01-10 15:32                 ` Vincent Guittot
2012-01-10 16:49               ` Vaidyanathan Srinivasan
2012-01-10 19:41               ` Ingo Molnar
2012-01-10 19:44                 ` Ingo Molnar
2012-01-10 16:54           ` Youquan Song
2012-01-10 16:51             ` Vaidyanathan Srinivasan
2012-01-10 19:01               ` Suresh Siddha
2012-01-11  3:52                 ` Vaidyanathan Srinivasan
2012-01-11 17:37                   ` Youquan Song
2012-01-10 16:44       ` Vaidyanathan Srinivasan
2012-01-09 11:12     ` Peter Zijlstra
2012-01-09 14:29       ` Vincent Guittot
2012-01-09 14:29         ` Vincent Guittot
2012-01-09 14:46         ` Peter Zijlstra
2012-01-10  2:12           ` Indan Zupancic
2012-01-10  9:26             ` Peter Zijlstra
2012-01-10  1:54         ` Suresh Siddha
2012-01-10  8:08           ` Vincent Guittot [this message]
2012-01-09 15:37 ` Greg KH

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