linux-kernel - Re: [PATCH RESEND v2 6/6] sched/fair: Remove unconditionally inactive code

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Date:	Fri, 1 Apr 2016 07:20:59 +0800
From:	Yuyang Du <yuyang.du@...el.com>
To:	bsegall@...gle.com
Cc:	peterz@...radead.org, mingo@...nel.org,
	linux-kernel@...r.kernel.org, pjt@...gle.com,
	morten.rasmussen@....com, vincent.guittot@...aro.org,
	dietmar.eggemann@....com, lizefan@...wei.com,
	umgwanakikbuti@...il.com
Subject: Re: [PATCH RESEND v2 6/6] sched/fair: Remove unconditionally
 inactive code

On Thu, Mar 31, 2016 at 10:53:02AM -0700, bsegall@...gle.com wrote:
> Yuyang Du <yuyang.du@...el.com> writes:
> 
> > The increased load resolution (fixed point arithmetic range) is
> > unconditionally deactivated with #if 0, so it is effectively broken.
> >
> > But the increased load range is still used somewhere (e.g., in Google),
> > so we keep this feature. The reconciliation is we define
> > CONFIG_CFS_INCREASE_LOAD_RANGE and it depends on FAIR_GROUP_SCHED and
> > 64BIT and BROKEN.
> >
> > Suggested-by: Ingo Molnar <mingo@...nel.org>
> > Signed-off-by: Yuyang Du <yuyang.du@...el.com>
> 
> The title of this patch "Remove unconditionally inactive code" is
> misleading since it's more like giving it a CONFIG.

Reasonable argument.

> 
> Also as a side note, does anyone remember/have a test for whatever got
> it turned off to begin with, given all the changes in load tracking and
> the load balancer and everything else?

It is this commit that turned it off:

Commit e4c2fb0d5776: "sched: Disable (revert) SCHED_LOAD_SCALE increase"