linux-kernel - Re: [PATCH 1/4] sched/fair: Generalize the load/util averages resolution definition

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Message-ID: <20151005070445.GA10526@gmail.com>
Date:	Mon, 5 Oct 2015 09:04:45 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Yuyang Du <yuyang.du@...el.com>
Cc:	peterz@...radead.org, linux-kernel@...r.kernel.org, pjt@...gle.com,
	bsegall@...gle.com, morten.rasmussen@....com,
	vincent.guittot@...aro.org, dietmar.eggemann@....com
Subject: Re: [PATCH 1/4] sched/fair: Generalize the load/util averages
 resolution definition


* Yuyang Du <yuyang.du@...el.com> wrote:

> +# define SCHED_RESOLUTION_SHIFT	10

>  #if 0 /* BITS_PER_LONG > 32 -- currently broken: it increases power usage under light load  */

Might be worth fixing?

Also, I noticed this:

> -# define SCHED_LOAD_RESOLUTION	10
> +# define SCHED_LOAD_SHIFT	(SCHED_RESOLUTION_SHIFT + SCHED_RESOLUTION_SHIFT)

So in the #if 0 (inactive) section we change it from 10 to 20 ...

> -# define SCHED_LOAD_RESOLUTION	0
> +# define SCHED_LOAD_SHIFT	(SCHED_RESOLUTION_SHIFT)
>  # define scale_load(w)		(w)
>  # define scale_load_down(w)	(w)
>  #endif
>  
> -#define SCHED_LOAD_SHIFT	(10 + SCHED_LOAD_RESOLUTION)

... then we change the actually active definition from 20 to 10?

Was that intended?

Please double check the 'make allyesconfig' disassembly of kernel/sched/built-in.o 
before/after this patch to make sure it does not change any code.

( No full allyesconfig build needed: 'make -j16 kernel/sched' should cut down on
  the build time. )

Thanks,

	Ingo
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