Messages in this thread |  | | Date | Mon, 26 Mar 2018 22:30:46 +0800 | From | Leo Yan <> | Subject | Re: [PATCH V2 0/7] CPU cooling device new strategies |
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On Thu, Mar 08, 2018 at 12:03:52PM +0000, Daniel Thompson wrote: > On Wed, Mar 07, 2018 at 07:57:17PM +0100, Daniel Lezcano wrote: > > >> The preliminary benchmarks show the following changes: > > >> > > >> On the hikey6220, dhrystone shows a throughtput increase of 40% for an > > >> increase of the latency of 16% while sysbench shows a latency increase > > >> of 5%. > > > > > > I don't follow these numbers. Throughput increase while injecting idle? > > > compared to what? percentages of what? Please be more specific to better > > > describer your work.. > > > > The dhrystone throughput is based on the virtual timer, when we are > > running, it is at max opp, so the throughput increases. But regarding > > the real time, it takes obviously more time to achieve as we are > > artificially inserting idle cycles. With the cpufreq governor, we run at > > a lower opp, so the throughput is less for dhrystone but it takes less > > time to achieve. > > > > Percentages are comparing cpufreq vs cpuidle cooling devices. I will > > take care of presenting the results in a more clear way in the next version. > > I think we should also note that the current hikey settings for cpufreq > are very badly tuned for this platform. It has a single temp threshold > and it jumps from max freq to min freq. > > IIRC Leo's work on Hikey thermals correctly it would be much better if > it used the power-allocator thermal governor or if if copied some of > the Samsung 32-bit platform by configuring the step governor with a > graduated with a slightly lower threshold that moves two stops back in > the OPP table (which is still fairly high clock speed... but it > thermally sustainable).
I think Daniel L. is working on this patch set with 'power-allocator' governor, and the parameters 'sustainable-power = <3326>' and 'dynamic-power-coefficient = <311>' are profiling value on Hikey platform. Now we only consider dynamic power and skip static leakage for 'power-allocator' governor. And all these parameters are merged into Linux mainline kernel.
Daniel L. could correct me if I misunderstand the testing conditions.
Thanks, Leo Yan
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