linux-kernel - Re: [PATCH] sched: fair: Improve PELT decay

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Message-ID: <20170322141626.isj3dlrimppwq2xv@hirez.programming.kicks-ass.net>
Date:   Wed, 22 Mar 2017 15:16:26 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Joel Fernandes <joelaf@...gle.com>
Cc:     linux-kernel@...r.kernel.org, Paul Turner <pjt@...gle.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Juri Lelli <Juri.Lelli@....com>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH] sched: fair: Improve PELT decay_load calculation comments

On Fri, Mar 10, 2017 at 12:23:41PM -0800, Joel Fernandes wrote:
> The PELT decay_load comments are a bit confusing, first of all
> the 1/2^N should be (1/2)^N so that the reader doesn't get confused.

I'm thinking you're confused. They're identical.

(1/2)^N = (2^-1)^N = 2^-N = 1/2^N

> Secondly, the y^N splitting into a 2-part decay factor deserves
> a better explanation. This patch improves the comments.

I find its actually harder to read.