linux-kernel - Re: [PATCH] sched: Introduce scaled capacity awareness in enqueue

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Message-ID: <20170601123745.llebc4ur23d7t4fw@hirez.programming.kicks-ass.net>
Date:   Thu, 1 Jun 2017 14:37:45 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Rohit Jain <rohit.k.jain@...cle.com>
Cc:     linux-kernel@...r.kernel.org, mingo@...hat.com,
        vincent.guittot@...aro.org, morten.rasmussen@....com,
        dietmar.eggemann@....com
Subject: Re: [PATCH] sched: Introduce scaled capacity awareness in enqueue

On Thu, Jun 01, 2017 at 02:28:27PM +0200, Peter Zijlstra wrote:
> On Wed, May 31, 2017 at 03:19:46PM -0700, Rohit Jain wrote:
> 
> > > > 2) This scaled capacity is normalized and mapped into buckets.
> > > Why?
> > 
> > This is done to deterministically define the CPUs which are low on
> > capacities. By mapping it into buckets it becomes easier to do a
> > percentile calculation.
> 
> *sigh*, you're really going to make me read and reverse engineer your
> horrible code.. :/

Blergh, I can't be arsed. It's got horrible style, its stuffed into the
loadavg code even though its completely unrelated to that particular
trainwreck and it adds more global state.

Global state is bad, very bad. And its not at all clear why you'd need
that to begin with.