linux-kernel - Re: [RFC PATCHC 0/3] sched/idle : find the idlest cpu with cpuidle info

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Message-ID: <20140415132510.GO11182@twins.programming.kicks-ass.net>
Date:	Tue, 15 Apr 2014 15:25:10 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	linux-kernel@...r.kernel.org, mingo@...e.hu,
	linux-pm@...r.kernel.org, alex.shi@...aro.org,
	vincent.guittot@...aro.org, morten.rasmussen@....com
Subject: Re: [RFC PATCHC 0/3] sched/idle : find the idlest cpu with cpuidle
 info

On Fri, Apr 04, 2014 at 01:43:00PM +0200, Rafael J. Wysocki wrote:
> > That's what this patch series is about.  The find_idlest_cpu code should 
> > look for the idle CPU with the shallowest idle state, or the one with 
> > the smallest load.  In this context "find_idlest_cpu" might become a 
> > misnomer.
> 
> Yes, clearly.  It should be called find_best_cpu or something like that.

Ha!, but for what purpose? We already have find_busiest_cpu() to find
the CPU to steal work from. The converse action, currently called
find_idlest_cpu() is finding the CPU where to put work.

'Best' is ambiguous in all regards, it doesn't convey the direction nor
the quality sorted on.

So while idlest might be somewhat of a misnomer, it at least conveys the
directional thing fairly well. Also we are still searching the least
busy, and preferable an idle, cpu. 'Idlest' being a superlative also
conveys the meaning of order.
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