linux-kernel - Re: [RFCv5 PATCH 18/46] arm: topology: Define TC2 energy and provide it to the scheduler

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Message-ID: <20150812103320.GW19282@twins.programming.kicks-ass.net>
Date:	Wed, 12 Aug 2015 12:33:20 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Morten Rasmussen <morten.rasmussen@....com>
Cc:	mingo@...hat.com, vincent.guittot@...aro.org,
	daniel.lezcano@...aro.org,
	Dietmar Eggemann <Dietmar.Eggemann@....com>,
	yuyang.du@...el.com, mturquette@...libre.com, rjw@...ysocki.net,
	Juri Lelli <Juri.Lelli@....com>, sgurrappadi@...dia.com,
	pang.xunlei@....com.cn, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, Russell King <linux@....linux.org.uk>
Subject: Re: [RFCv5 PATCH 18/46] arm: topology: Define TC2 energy and provide
 it to the scheduler

On Tue, Jul 07, 2015 at 07:24:01PM +0100, Morten Rasmussen wrote:
> +static struct capacity_state cap_states_cluster_a7[] = {
> +	/* Cluster only power */
> +	 { .cap =  150, .power = 2967, }, /*  350 MHz */
> +	 { .cap =  172, .power = 2792, }, /*  400 MHz */
> +	 { .cap =  215, .power = 2810, }, /*  500 MHz */
> +	 { .cap =  258, .power = 2815, }, /*  600 MHz */
> +	 { .cap =  301, .power = 2919, }, /*  700 MHz */
> +	 { .cap =  344, .power = 2847, }, /*  800 MHz */
> +	 { .cap =  387, .power = 3917, }, /*  900 MHz */
> +	 { .cap =  430, .power = 4905, }, /* 1000 MHz */
> +	};

So can I suggest a SCHED_DEBUG validation of the data provided?

Given the above table, it _never_ makes sense to run at .cap=150, it
equally also doesn't make sense to run at .cap = 301.

So please add a SCHED_DEBUG test on domain creation that validates that
not only is the .cap monotonically increasing, but the .power is too.
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