linux-kernel - Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity

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Message-ID: <20150910100604.GT3644@twins.programming.kicks-ass.net>
Date:	Thu, 10 Sep 2015 12:06:04 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Yuyang Du <yuyang.du@...el.com>
Cc:	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steve Muckle <steve.muckle@...aro.org>,
	Morten Rasmussen <Morten.Rasmussen@....com>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
	"mturquette@...libre.com" <mturquette@...libre.com>,
	"rjw@...ysocki.net" <rjw@...ysocki.net>,
	Juri Lelli <Juri.Lelli@....com>,
	"sgurrappadi@...dia.com" <sgurrappadi@...dia.com>,
	"pang.xunlei@....com.cn" <pang.xunlei@....com.cn>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by
 capacity_orig

On Thu, Sep 10, 2015 at 03:07:48AM +0800, Yuyang Du wrote:
> On Tue, Sep 08, 2015 at 02:52:05PM +0200, Peter Zijlstra wrote:
> >  
> > +#if (SCHED_LOAD_SHIFT - SCHED_LOAD_RESOLUTION) != 10 || SCHED_CAPACITY_SHIFT != 10
> > +#error "load tracking assumes 2^10 as unit"
> > +#endif
> > +
> 
> Sorry for late response. I might already missed somthing.
> 
> But I got a bit lost here, with:
> 
> #define SCHED_LOAD_SHIFT        (10 + SCHED_LOAD_RESOLUTION)
> #define SCHED_CAPACITY_SHIFT    10
> 
> the #if is certainly false.

That is intended, triggering #error would be 'bad'.

The reason for this bit is to raise a stink if someone 'accidentally'
changes one of these values and expects things to just work.
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