Messages in this thread |  | | From | "Doug Smythies" <> | Subject | RE: Performance of low-cpu utilisation benchmark regressed severely since 4.6 | Date | Fri, 21 Apr 2017 23:29:06 -0700 |
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On 2017.04.20 18:18 Rafael wrote: > On Thursday, April 20, 2017 07:55:57 AM Doug Smythies wrote: >> On 2017.04.19 01:16 Mel Gorman wrote: >>> On Fri, Apr 14, 2017 at 04:01:40PM -0700, Doug Smythies wrote: >>>> Hi Mel, > > [cut] > >>> And the revert does help albeit not being an option for reasons Rafael >>> covered. >> >> New data point: Kernel 4.11-rc7 intel_pstate, powersave forcing the >> load based algorithm: Elapsed 3178 seconds. >> >> If I understand your data correctly, my load based results are the opposite of yours. >> >> Mel: 4.11-rc5 vanilla: Elapsed mean: 3750.20 Seconds >> Mel: 4.11-rc5 load based: Elapsed mean: 2503.27 Seconds >> Or: 33.25% >> >> Doug: 4.11-rc6 stock: Elapsed total (5 runs): 2364.45 Seconds >> Doug: 4.11-rc7 force load based: Elapsed total (5 runs): 3178 Seconds >> Or: -34.4% > > I wonder if you can do the same thing I've just advised Mel to do. That is, > take my linux-next branch: > > git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next > > (which is new material for 4.12 on top of 4.11-rc7) and reduce > INTEL_PSTATE_DEFAULT_SAMPLING_INTERVAL (in intel_pstate.c) in it by 1/2 > (force load-based if need be, I'm not sure what PM profile of your test system > is).
I did not need to force load-based. I do not know how to figure it out from an acpidump the way Srinivas does. I did a trace and figured out what algorithm it was using from the data.
Reference test, before changing INTEL_PSTATE_DEFAULT_SAMPLING_INTERVAL: 3239.4 seconds.
Test after changing INTEL_PSTATE_DEFAULT_SAMPLING_INTERVAL: 3195.5 seconds.
By far, and with any code, I get the fastest elapsed time, of course next to performance mode, but not by much, by limiting the test to only use just 1 cpu: 1814.2 Seconds. (performance governor, restated from a previous e-mail: 1776.05 seconds)
... Doug
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