linux-kernel - Re: [PATCH 0/2 v4] sched: Rewrite per entity runnable load average tracking

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Message-ID: <20140730105707.GC3001@e103034-lin>
Date:	Wed, 30 Jul 2014 11:57:07 +0100
From:	Morten Rasmussen <morten.rasmussen@....com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Yuyang Du <yuyang.du@...el.com>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"pjt@...gle.com" <pjt@...gle.com>,
	"bsegall@...gle.com" <bsegall@...gle.com>,
	"arjan.van.de.ven@...el.com" <arjan.van.de.ven@...el.com>,
	"len.brown@...el.com" <len.brown@...el.com>,
	"rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
	"alan.cox@...el.com" <alan.cox@...el.com>,
	"mark.gross@...el.com" <mark.gross@...el.com>,
	"fengguang.wu@...el.com" <fengguang.wu@...el.com>
Subject: Re: [PATCH 0/2 v4] sched: Rewrite per entity runnable load average
 tracking

On Wed, Jul 30, 2014 at 11:21:28AM +0100, Peter Zijlstra wrote:
> On Wed, Jul 30, 2014 at 11:13:31AM +0100, Morten Rasmussen wrote:
> > It is a very real problem when user-space uses priorities extensively
> > like Android does. Tasks related to audio run at very high priorities
> > but only for a very short amount of time, but due the to priority
> > scaling their load ends up being several times higher than tasks running
> > all the time at normal priority. Hence task load is a very poor
> > indicator of utilization.
> 
> FWIW Android (which I think does this through binder) is utterly insane
> in this regard. But yes, we have to live with it.

I agree that its use of priorities seems a bit extreme. I'm not trying
to defend it in any way :-) 
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