Messages in this thread | | | Subject | Re: [PATCH v4 1/6] x86,sched: Add support for frequency invariance | From | Giovanni Gherdovich <> | Date | Tue, 26 Nov 2019 16:20:00 +0100 |
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On Mon, 2019-11-25 at 21:59 -0800, Doug Smythies wrote: > [...] > The issue with the schedutil governor not working properly in the 5.4 RC series > appears to be hardware dependant. > > My test computer is Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz., Sandy Bridge. > On a temporary basis, I acquired a computer with an > Intel(R) Core(TM) i5-4460 CPU @ 3.20GHz, Haswell, > and schedutil governor behaviour with the exact same kernels is fine: > > That "gitsource" test, "make test" 6 times, first run thrown out: > > Kernel 5.4 intel_cpufreq/schedutil: 3411.8 seconds > Kernel 5.4 + gg 6 intel_cpufreq/schedutil: 1696.7 seconds > Ratio: 0.49 > Recall you got a ratio of 0.49 with 5th generation, Broadwell.
It's good to hear that we're getting the same performance numbers for this patchset on all hardware that is not a Sandy Bridge. Thanks for double checking, independent verification is always valuable.
Now, regarding the 5.4 regression for schedutil you see on Sandy Bridge: can we move this to the kernel bugzilla? Would you care to open a bug there and CC me to it? If it's reproducible we should assess it and see what can be done.
I've tried gitsource on 5.3 versus 5.4, using intel_cpufreq + schedutil; I don't see the drop you're observing, but I don't have a Sandy Bridge readily available. This is what I see:
Arithmetic mean of elapsed time for gitsource over 5 iterations (seconds):
microarch v5.3 (baseline) v5.4 ------------------------------------------------------------------ Haswell 1337.84 +- 0.11% 1336.35 +- 0.12% ( 0.11%) Broadwell 1335.42 +- 0.08% 1352.54 +- 0.03% ( -1.28%) Skylake 887.03 +- 1.02% 870.90 +- 1.19% ( 1.82%)
I'm looking around for a Sandy Bridge but I can make no promises at the moment.
Thanks, Giovanni
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