Hi All, I got inputs from couple of folks for this testing. Based on this, I have the opinion that the issue exists even with x86 platforms as well but with lesser severity (worstcase 89%), most probably due to optimized governor parameters (esp cpufreq_transition_latency). Also I figured out that there is an interesting patch from David C Niemi (http://kerneltrap.org/mailarchive/linux-kernel/2010/10/6/4628889/thread) which helps in reducing frequent OPP changes when there is high load in the system which helped to improve ondemand performance.
After optimizing cpufreq_transition_latency for omap along with applying above patch, cpufreq-bench results on OMAP are much better. Attached files have the results. cpufreq-bench results without optimization on OMAP. Round 1 - 41.11% Round 2 - 41.61% Round 3 - 40.79% Round 4 - 41.17% Round 5 - 52.58% Time spent in different P states: 300M - 12.26% 600M - .28% 800M - 0% 1000M - 87.33% cpufreq-bench results with optimization on OMAP. Round 1 - 90.24% Round 2 - 94.48% Round 3 - 96.06% Round 4 - 96.6% Round 5 - 86.89% Time spent in different P states: 300M - 3.26% 600M - 0.4% 800M - 0% 1000M - 96.33% Special thanks to Mark and Vincent for their testing and feedbacks. Attached docs have detailed report log. Regards Vishwa On Tue, Nov 16, 2010 at 11:27 PM, Mark Wilcox <m_p_wil...@yahoo.co.uk> wrote: > Hi Vishwanath, > >> I am trying to investigate ondemand governor’s limitation in Linux kernel. >> As part of that, I have found a tool called cpufreq-bench which can be >> used >> to determine the performance degradation due to ondemand governor compared >> to performance governor. >> >> I would need some of your help to run this test bench on some of recent >> X86 >> platforms that have support for many P states. (My PC is little old which >> has only 2 p-states (2.8GHz & 3.4 GHz), so performance degradation is not >> much visible). >> tarball with cpufreqbench and readme is available at >> http://people.linaro.org/~amitk/cpufreq.tgz > > I'm just a lurker on the list at the moment but thought I could easily do > this to help out. Log attached. > > A little feedback on the instructions - cpufreq-bench's Makefile doesn't > have an install target although the instructions say to do make; make > install, I copied the binary manually. > > Copying these results to the list as requested but is that really necessary > for everyone? Could you summarise the results for us all when you've got > enough please? > > Mark > > ________________________________ > From: Vishwanath Sripathy <vishwanath.sripa...@linaro.org> > To: "linaro-dev@lists.linaro.org" <linaro-dev@lists.linaro.org> > Sent: Tue, 16 November, 2010 13:07:46 > Subject: Re: cpufreq-bench test on X86 platforms > > Hi All, > > tarball with cpufreqbench and readme is available at > http://people.linaro.org/~amitk/cpufreq.tgz > > Vishwanath > On Tue, Nov 16, 2010 at 3:37 PM, Sripathy, Vishwanath > <vishwanath...@ti.com> wrote: >> All, >> >> >> >> I am trying to investigate ondemand governor’s limitation in Linux kernel. >> As part of that, I have found a tool called cpufreq-bench which can be >> used >> to determine the performance degradation due to ondemand governor compared >> to performance governor. >> >> >> >> I have used this tool on OMAP platforms and able to see the issue. Now I >> would like to demonstrate this issue on x86 platform to conclude that it’s >> a >> generic governor problem and nothing specific to ARM based SOCs. >> >> >> >> I would need some of your help to run this test bench on some of recent >> X86 >> platforms that have support for many P states. (My PC is little old which >> has only 2 p-states (2.8GHz & 3.4 GHz), so performance degradation is not >> much visible). >> >> >> >> More details on the tool and test procedure can be found at >> >> >> https://blueprints.edge.launchpad.net/linaro-pm-wg/+spec/cpufreq-ondemand-governor >> >> >> >> Pls ping me if you need any assistance in testing. >> >> Looking forward for your test results. >> >> >> >> Regards >> >> Vishwanath >> >> >> >> _______________________________________________ >> linaro-dev mailing list >> linaro-dev@lists.linaro.org >> http://lists.linaro.org/mailman/listinfo/linaro-dev >> >> > > _______________________________________________ > linaro-dev mailing list > linaro-dev@lists.linaro.org > http://lists.linaro.org/mailman/listinfo/linaro-dev > >
cpufreq_opt.log
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cpufreq_noopt.log
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