linux-kernel - Re: [tip:sched/core] sched/fair: Clean up scale confusion

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Date:	Fri, 13 May 2016 03:42:24 +0800
From:	Yuyang Du <yuyang.du@...el.com>
To:	morten.rasmussen@....com, linux-kernel@...r.kernel.org,
	efault@....de, wanpeng.li@...mail.com, peterz@...radead.org,
	hpa@...or.com, torvalds@...ux-foundation.org, tglx@...utronix.de,
	mingo@...nel.org
Cc:	vincent.guittot@...aro.org, bsegall@...gle.com
Subject: Re: [tip:sched/core] sched/fair: Clean up scale confusion

On Thu, May 12, 2016 at 03:31:27AM -0700, tip-bot for Peter Zijlstra wrote:
> Commit-ID:  1be0eb2a97d756fb7dd8c9baf372d81fa9699c09
> Gitweb:     http://git.kernel.org/tip/1be0eb2a97d756fb7dd8c9baf372d81fa9699c09
> Author:     Peter Zijlstra <peterz@...radead.org>
> AuthorDate: Fri, 6 May 2016 12:21:23 +0200
> Committer:  Ingo Molnar <mingo@...nel.org>
> CommitDate: Thu, 12 May 2016 09:55:33 +0200
> 
> sched/fair: Clean up scale confusion
> 
> Wanpeng noted that the scale_load_down() in calculate_imbalance() was
> weird. I agree, it should be SCHED_CAPACITY_SCALE, since we're going
> to compare against busiest->group_capacity, which is in [capacity]
> units.
>
> Reported-by: Wanpeng Li <wanpeng.li@...mail.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> Cc: Mike Galbraith <efault@....de>
> Cc: Morten Rasmussen <morten.rasmussen@....com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Yuyang Du <yuyang.du@...el.com>
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Ingo Molnar <mingo@...nel.org>

It is good that this issue is addressed and patch merged, however, for the
record, Vincent has already had a solution for this, and we had a patch,
including other cleanups (the latest version is: https://lkml.org/lkml/2016/5/3/925).
And I think Ben first pointed this out (and we then attempted to address it)
as far as I can tell.