linux-kernel - Re: [PATCH v3 2/4] sched/fair: Make CFS bandwidth controller burstable

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Message-ID: <YFCOiiEi84ioMXfA@hirez.programming.kicks-ass.net>
Date:   Tue, 16 Mar 2021 11:55:06 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     changhuaixin <changhuaixin@...ux.alibaba.com>
Cc:     Benjamin Segall <bsegall@...gle.com>, dietmar.eggemann@....com,
        juri.lelli@...hat.com, khlebnikov@...dex-team.ru,
        open list <linux-kernel@...r.kernel.org>, mgorman@...e.de,
        mingo@...hat.com, pauld@...head.com, Paul Turner <pjt@...gle.com>,
        rostedt@...dmis.org, Shanpei Chen <shanpeic@...ux.alibaba.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        xiyou.wangcong@...il.com
Subject: Re: [PATCH v3 2/4] sched/fair: Make CFS bandwidth controller
 burstable

On Fri, Mar 12, 2021 at 09:54:33PM +0800, changhuaixin wrote:
> > On Mar 10, 2021, at 9:04 PM, Peter Zijlstra <peterz@...radead.org> wrote:

> > There's already an #ifdef block that contains that bandwidth_slice
> > thing, see the previous hunk, so why create a new #ifdef here?
> > 
> > Also, personally I think percentages are over-represented as members of
> > Q.
> > 
> Sorry, I don't quite understand the "members of Q". Is this saying that the percentages
> are over-designed here?

You know the number groups (in order): N, Z, Q, R, C, H, O.

Percent being 1/100 is a fraction and thus part of Q (and anything
higher ofcourse).

Some people seem to think percent is magical and special. It's just a
fraction like the inifinite many others in Q. It's also a very crappy
one when we consider computers.

Basically I hate percentages, they're nothing special and often employed
where they should not be.