Messages in this thread | | | Subject | Re: [PATCH V2 0/7] CPU cooling device new strategies | From | Daniel Lezcano <> | Date | Tue, 27 Mar 2018 11:35:42 +0200 |
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On 26/03/2018 16:30, Leo Yan wrote: > 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.
Well, the first iteration is without the powerallocator governor API. It was tested with the step-wise governor only. But you are right by saying it will use the dynamic-power-coefficient and sustainable-power and will implement the power allocator version of the API. I'm working on the power allocator version for the idle injection + OPP change as we need to compute the capacity equivalence between the idle-injection cycles + OPP and the lower OPP in order to change the OPP for optimized power / performance trade-off.
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