linux-kernel - Re: [PATCH] sched: fix sched_feat for !SCHED

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Date:   Tue, 7 Nov 2017 20:05:05 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Patrick Bellasi <patrick.bellasi@....com>
Cc:     linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Chris Redpath <chris.redpath@....com>
Subject: Re: [PATCH] sched: fix sched_feat for !SCHED_DEBUG builds

On Tue, Nov 07, 2017 at 04:06:58PM +0000, Patrick Bellasi wrote:
> For this mechanism to properly work it's required for the compiler to
> have full access, from each translation unit, to whatever is the value
> defined by the sched_feat macro. 

> Statistics on the reported completion time:
> 
>                  count     mean       std     min       99%     max
> v4.14-rc8         30.0  15.7831  0.176032  15.442  16.01226  16.014
> v4.14-rc8+patch   30.0  15.5033  0.189681  15.232  15.93938  15.962
> 
> show a 1.8% speedup on average completion time and 0.5% speedup in the
> 99 percentile.
> 

Ack