linux-kernel - Re: [RESEND PATCH V5 0/8] remove cpu

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Message-ID: <20140506114315.GG11096@twins.programming.kicks-ass.net>
Date:	Tue, 6 May 2014 13:43:15 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Alex Shi <alex.shi@...aro.org>
Cc:	Morten Rasmussen <morten.rasmussen@....com>,
	Fengguang Wu <fengguang.wu@...el.com>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"vincent.guittot@...aro.org" <vincent.guittot@...aro.org>,
	"daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
	"efault@....de" <efault@....de>,
	"wangyun@...ux.vnet.ibm.com" <wangyun@...ux.vnet.ibm.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mgorman@...e.de" <mgorman@...e.de>
Subject: Re: [RESEND PATCH V5 0/8] remove cpu_load idx

On Tue, May 06, 2014 at 04:33:38PM +0800, Alex Shi wrote:
> 
> > 
> > Maybe the predication is reasonable on per task history. but on a cpu
> > load history, with many tasks rebalance. No testing show current method
> > is helpful.
> > 
> > For task load change, scheduler has no idea for its future except guess
> > from its history. but for cpu load change, scheduler know this from task
> > wakeup and balance, which both under control and its aim.
> > 
> > 
> > I think the first patch of this serial has the same effect of LB_LIAS
> > disable. and previous result show performance is good.
> > 
> > Anyway, I just pushed the following patch to github, maybe fengguang's
> > testing system will care this.
> 
> Fengguang,
> 
> Are there any performance change on
> https://github.com/alexshi/power-scheduling.git noload repository?

You forgot to qualify that with the important bit; on _large_ systems.
Esp. non fully connected numa boxen. Also, I'm not sure Wu has workloads
that are typical of such systems -- even if he has such machines, which
I don't know either.

Enterprise distro testing has _some_ of that, but the very sad truth is
that most enterprise users lag behind at least a full release cycle. So
by the time people start using the kernel, its so old nobody really
cares anymore :-(



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