Messages in this thread | | | Date | Mon, 31 Oct 2016 08:07:46 -0700 | From | Vikram Mulukutla <> | Subject | Re: [RFC PATCH 0/3] sched: Introduce Window Assisted Load Tracking |
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On 2016-10-28 01:49, Peter Zijlstra wrote: > On Fri, Oct 28, 2016 at 12:57:05AM -0700, Vikram Mulukutla wrote: >> On 2016-10-28 00:49, Peter Zijlstra wrote: >> >On Fri, Oct 28, 2016 at 12:10:39AM -0700, Vikram Mulukutla wrote: >> >>This RFC patch has been tested on live X86 machines with the following >> >>sanity >> >>and benchmark results (thanks to Juri Lelli, Dietmar Eggeman, Patrick >> >>Bellasi >> >>for initial code reviews): >> >> >> >>(Tested on an Intel i7 2nd generation CPU, 8GB RAM, Nvidia GTX950Ti >> >>graphics, >> >>with the same frequency list as above. Running Ubuntu 16.04 on a v4.8.2 >> >>baseline. WALT window size was 10ms. Only deltas above 3% are considered >> >>non-noise.Power measured with Intel RAPL counters) >> > >> >Was this comparison done using the use_walt_metric sysctl knob? >> >> Yes, it was. You will want to see numbers against a pure 4.8.2 without >> any >> of the WALT code, correct? > > Yep, because with the sysctl we still run all the accounting code. So > esp things like the hackbench run are meaningless (note that even the > CONFIG thing doesn't take out everything). > > Also, I think it makes sense to always (also) compare against the > "performance" governor. That way you can see the drop in absolute > performance etc..
Ok, here are some numbers. I should be able to get the rest during the week. The averages are pretty close, so I figured I would include some percentile numbers. PELT and WALT numbers are with schedutil. On average it seems we're introducing about 0.5% overhead with the current additional accounting.
Test: perf bench sched messaging -g 50 -l 5000 +-------------+-------------+----------+----------+-----------+ | 4.8.2-walt | Performance | Ondemand | PELT | WALT(10ms)| +-------------+-------------+----------+----------+---------- + | | | | | | | 90th | 17.077 | 17.088 | 17.088 | 17.159 | | | | | | | | 96th | 17.117 | 17.421 | 17.198 | 17.343 | | | | | | | | Average | 16.910 | 16.916 | 16.937 | 16.962 | | | | | | | +-------------+-------------+----------+----------+-----------+ | 4.8.2-raw | Performance | Ondemand | PELT | WALT(10ms)| +-------------+-------------+----------+----------+-----------+ | | | | | | | 90th | 16.919 | 17.1694 | 16.986 | 0 | | | | | | | | 96th | 16.980 | 17.364 | 17.052 | 0 | | | | | | | | Average | 16.841 | 16.902 | 16.860 | 0 | +-------------+-------------+----------+----------+-----------+
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