linux-kernel - Re: [PATCH v3 05/22] sched: remove domain iterations in fork/exec/wake

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Message-ID: <1358301280.23348.6.camel@liguang.fnst.cn.fujitsu.com>
Date:	Wed, 16 Jan 2013 09:54:40 +0800
From:	li guang <lig.fnst@...fujitsu.com>
To:	Alex Shi <alex.shi@...el.com>
Cc:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Morten Rasmussen <Morten.Rasmussen@....com>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"peterz@...radead.org" <peterz@...radead.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"arjan@...ux.intel.com" <arjan@...ux.intel.com>,
	"bp@...en8.de" <bp@...en8.de>, "pjt@...gle.com" <pjt@...gle.com>,
	"namhyung@...nel.org" <namhyung@...nel.org>,
	"efault@....de" <efault@....de>,
	"vincent.guittot@...aro.org" <vincent.guittot@...aro.org>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 05/22] sched: remove domain iterations in
 fork/exec/wake

在 2013-01-15二的 10:34 +0800，Alex Shi写道：
> On 01/14/2013 05:03 PM, li guang wrote:
> >>> > > This corner case may occur after "[PATCH v3 03/22] sched: fix
> >>> > > find_idlest_group mess logical" brought in the local sched_group bias,
> >>> > > and assume balancing runs on cpux2.
> >>> > > ideally,  find_idlest_group should find the real idlest(this case: sgy),
> >>> > > then, this patch is reasonable.
> >>> > > 
> >> > 
> >> > Sure. but seems it is a bit hard to go down the idlest group.
> >> > 
> >> > and the old logical is real cost too much, on my 2 socket NHM/SNB
> >> > server, hackbench can increase 2~5% performance. and no clean
> >> > performance on kbuild/aim7 etc.
> > what about remove local group bias?
> 
> 
> Any theory profit for non local group? Usually, bias toward local group
> will has cache locality profit.
> 

but the disadvantage is miss correct balance sometime,
if mostly like you said before it will bring in better performance,
that's fine, I have no strong statistic to do more profound analysis.


-- 
regards!
li guang

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