linux-kernel - Re: [RFC v2 0/3][TESTS] LAB: Support for Legacy Application Booster governor

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Date:	Fri, 24 May 2013 07:56:40 +0200
From:	Lukasz Majewski <l.majewski@...sung.com>
To:	Lukasz Majewski <l.majewski@...sung.com>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>,
	Jonghwa Lee <jonghwa3.lee@...sung.com>,
	"Rafael J. Wysocky" <rjw@...k.pl>, linux-kernel@...r.kernel.org,
	cpufreq@...r.kernel.org, linux-pm@...r.kernel.org,
	Vicent Guittot <vincent.guittot@...aro.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	MyungJoo Ham <myungjoo.ham@...sung.com>,
	Lukasz Majewski <l.majewski@...ess.pl>
Subject: Re: [RFC v2 0/3][TESTS] LAB: Support for Legacy Application Booster
 governor - tests results

Hi Viresh,

> 
> > On 22 May 2013 15:57, Lukasz Majewski <l.majewski@...sung.com>
> > wrote:
> > >> On 3 May 2013 19:37, Jonghwa Lee <jonghwa3.lee@...sung.com>
> > >> wrote:
> > 
> > > I think, that overclocking support is crucial here. As you pointed
> > > out
> > > - ondemand and conservative benefit from it. Therefore, I would
> > > urge for its mainline acceptance.
> > >
> > > (code for reference)
> > > http://thread.gmane.org/gmane.linux.kernel/1484746/match=cpufreq
> > >
> > > In this RFC (patch 1/3), I've decided to put the burden of
> > > overclocking support to platform code (cpufreq/exynos-cpufreq.c
> > > and cpufreq/exynos4x12-cpufreq.c).
> > >
> > > Those changes aren't intrusive for other boards/archs. Moreover
> > > overclocking is closely related to processor clocking/power
> > > dissipation capabilities, so SoC specific code is a good place for
> > > it.
> > >
> > >
> > > What DO need a broad acceptance is the overclocking API proposed
> > > at: include/linux/cpufreq.h
> > >
> > > This introduces interface to which others will be bind. It
> > > shouldn't be difficult to implement overclocking at other SoCs (as
> > > it was proposed for Exynos).
> > >
> > > Feedback is welcome, since I might have overlooked oddities
> > > present at other SoCs.
> > 
> > Hi..
> > 
> > I am not talking about the minute details here... for example I
> > didn't like the way overclocking support is implemented... It has to
> > be a bit more framework oriented then driver...
> > 
> > What I am thinking right now is if it is worth to add both the
> > features you are trying. i.e. overclocking and LAB..
> > 
> > So, requested you to give some figures... of ondemand with and
> > without overclocking... Leave LAB for now...

As you wished, I've provided relevant data for overclocking.

Would you be so kind and comment on them?



> > 
> > Then we can give LAB a try with above...
> 
> Test HW Exynos4412 (4 Cores):
> Kernel 3.8.3
> 
> Ondemand max freq: 1.4 GHz
> Overclock max freq: 1.5 GHz
> 
> 
> Ondemand improvement with and without overclocking (called by us
> TurboBoost - TB):
> 
> Dhrystone has been built according to:
> http://zenit.senecac.on.ca/wiki/index.php/Dhrystone_howto
> It's Makefile is also attached.
> ------------------------------------------------
> 
> Dhrystone	# of Threads			
> 		1	2	3	4
> ondemand	2054794	2061855	2097902	2090592
> ondemand + TB	2290076	2205882	2281368 2290076
> 
> Improvement:	10%	7%	8%	9%
> -------------------------------------------------
> 
> Electric charge [C]
> (Avg) [A] * [second]	# of Threads			
> 		1	2	3	4
> ondemand	1,334	1,837	2,296	3,096
> ondemand + TB	1,401	2,2025	2,907	4,34976
> 								
> Power cost:	5%	17%	21%	29%
> -------------------------------------------------
> 
> Execution time [second]	# of Threads			
> 		1	2	3	4
> ondemand	2,827	2,8	2,787	2,872
> ondemand + TB	2,622	2,694	2,667	2,76
> 				
> 				
> Speedup:	-7%	-4%	-4%	-4%
> 
> -------------------------------------------------
> 
> "Real life" example:
> time tar -czf linux-3.9.1.tar.gz linux-3.9.1/
> 
> 		Avg current[mA]		Time[s]
> Ondemand:	460			153	
> Ondemand + TB:	512			144
> 
> Result:		+10%			-6%
> 
> 
> 
> Conclusion: 
> 
> The main use case for TB is to speed up execution of tasks packed to
> one core. Other cores are then in IDLE state.
> 
> For a single core we can safely overclock, since we will not exceed
> its power consumption and thermal limits.
> 
> 


-- 
Best regards,

Lukasz Majewski

Samsung R&D Poland (SRPOL) | Linux Platform Group
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