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Message-ID: <509A5C1D.601@intel.com>
Date: Wed, 07 Nov 2012 21:03:25 +0800
From: Alex Shi <alex.shi@...el.com>
To: Luming Yu <luming.yu@...il.com>
CC: rob@...dley.net, mingo@...hat.com, peterz@...radead.org,
suresh.b.siddha@...el.com, arjan@...ux.intel.com,
vincent.guittot@...aro.org, tglx@...utronix.de,
gregkh@...uxfoundation.org, andre.przywara@....com, rjw@...k.pl,
paul.gortmaker@...driver.com, akpm@...ux-foundation.org,
paulmck@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
cl@...ux.com, pjt@...gle.com
Subject: Re: [RFC PATCH 1/3] sched: add sched_policy and it's sysfs interface
On 11/06/2012 11:20 PM, Luming Yu wrote:
> On Tue, Nov 6, 2012 at 8:09 AM, Alex Shi <alex.shi@...el.com> wrote:
>> This patch add the power aware scheduler knob into sysfs:
>
> The problem is user doesn't know how to use this knob.
>
> Based on what data, people could select one policy which could be surely
> better than another?
>
> "Packing small tasks" approach could be better and more intelligent.
> http://thread.gmane.org/gmane.linux.kernel/1348522
It is not conflict with this patchset. :)
>
> Just some random thoughts, as I didn't have chance to look into the
> details of that patch set yet. But to me, we need to exploit the fact
> that we could automatically bind a group of tasks on minimal set of
> CPUs that can provide sufficient CPU cycles that are comparable to
> a"cpu- run-average" that the task group can get in pure CFS situation
> in a given period, until we see more CPU is needed.Then we probably
> can maintain required CPU power available to the corresponding
> workload, while leaving all other CPUs into power saving mode. The
> problem is historical data suggested pattern could become invalid in
> future, then we need more CPUs in future..I think this is the point we
> need to know before spread or not-spread decision ...if spread would
> not help CPU-run-average ,we don't need waste CPU power..but I don't
> know how hard it could be. But I'm pretty sure sysfs knob is harder.
> :-) /l
>
--
Thanks
Alex
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