linux-kernel - Re: [RFC PATCH v2 0/4] CPUs capacity information for heterogeneous systems

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Message-ID: <20160120102237.GN8573@e106622-lin>
Date:	Wed, 20 Jan 2016 10:22:37 +0000
From:	Juri Lelli <juri.lelli@....com>
To:	Mark Brown <broonie@...nel.org>
Cc:	Steve Muckle <steve.muckle@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Mark Rutland <mark.rutland@....com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Will Deacon <will.deacon@....com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Rob Herring <robh+dt@...nel.org>,
	Sudeep Holla <sudeep.holla@....com>,
	Morten Rasmussen <morten.rasmussen@....com>,
	LAK <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC PATCH v2 0/4] CPUs capacity information for heterogeneous
 systems

On 19/01/16 21:10, Mark Brown wrote:
> On Tue, Jan 19, 2016 at 11:48:15AM -0800, Steve Muckle wrote:
> > On 01/19/2016 06:29 AM, Juri Lelli wrote:
> 
> > > I'm generally seeing ~1sec increase in boot time for 1 and practically
> > > no difference for 2 (even after having added patches that provide
> > > runtime performance improvements).
> 
> > One second is considerable IMO. Aside from the general desire to have
> > shorter boot times on any platform there are environments like
> > automotive where boot time is critical.
> 
> Yeah, definitely.  Is this actually blocking boot and if so can we
> arrange to do this in parallel with other activity (with likely knock on
> effects on reproducibility...)?

No, this goes in parallel. That's also showed by the fact that the
benchmarking thing itself usually takes more that 1 sec, but it seems to
impact for that amount of time only.