From: Arjan van de Ven <arjan@linux.intel.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>,
Youquan Song <youquan.song@intel.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
linux-kernel@vger.kernel.org, tglx@linutronix.de, hpa@zytor.com,
akpm@linux-foundation.org, stable@vger.kernel.org,
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 06:32:16 -0800 [thread overview]
Message-ID: <4F0C4BF0.9090809@linux.intel.com> (raw)
In-Reply-To: <20120110091805.GA28024@elte.hu>
On 1/10/2012 1:18 AM, Ingo Molnar wrote:
>
> * Suresh Siddha <suresh.b.siddha@intel.com> wrote:
>
>> On Tue, 2012-01-10 at 00:58 -0500, Youquan Song wrote:
>>> Thanks Peter! Here is the patch.
>>
>> Youquan, As far as I know both the
>> sched_smt_power_savings/sched_mc_power_savings are broken for atleast an
>> year.
>
> We want a single knob, sched_power_savings - with the mc_ and
> smt_ ones still kept and aliased to sched_power_savings, for
> compatibility reasons.
>
> As Peter said, the other reasonable option is to have no knob at
> all and restart this code from scratch.
>
> The other thing we should do is to add sane defaults: to turn on
> sched_power_savings *AUTOMATICALLY* when a system is obviously
> battery driven and turn it off when the system is obviously AC
> driven. User-space can still implement policy and override the
> kernel's default, but there's absolutely no excuse to not offer
> this default ourselves.
a very good default would be to keep all tasks on one package until half
the cores in the package are busy, and then start spreading out.
I suspect that'll be the 90% case coverage.
next prev parent reply other threads:[~2012-01-10 14:32 UTC|newest]
Thread overview: 36+ 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
2012-01-10 0:14 ` 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 [this message]
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 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 14:46 ` 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
2012-01-09 15:37 ` Greg KH
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