From: Arjan van de Ven <arjan@linux.intel.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>,
Suresh Siddha <suresh.b.siddha@intel.com>,
Youquan Song <youquan.song@intel.com>,
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 06:54:48 -0800 [thread overview]
Message-ID: <4F0C5138.5010109@linux.intel.com> (raw)
In-Reply-To: <1326206478.2442.111.camel@twins>
On 1/10/2012 6:41 AM, Peter Zijlstra wrote:
> On Tue, 2012-01-10 at 06:32 -0800, Arjan van de Ven wrote:
>>
>> 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.
>
> Does that still make sense when there's strong NUMA preference? By
> forcing stuff on a single package you increase the number of remote
> memory fetches (which generally generate more stalls), also the memory
> controllers need to stay awake anyway.
the memory controllers need to stake regardless of what you do;
it's more a memory bandwidth kind of thing.
if you have an enormous numa factor (>= 10 or so), then you really need
a completely different policy I suspect.
Thankfully those are rare.
next prev parent reply other threads:[~2012-01-10 14:54 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
2012-01-10 14:41 ` Peter Zijlstra
2012-01-10 14:54 ` Arjan van de Ven [this message]
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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