Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [RFC][PATCH 6/7] cpufreq: schedutil: Add iowait boosting | Date | Wed, 03 Aug 2016 01:03:23 +0200 |
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On Monday, August 01, 2016 06:35:31 PM Steve Muckle wrote: > On Mon, Aug 01, 2016 at 01:37:59AM +0200, Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > Modify the schedutil cpufreq governor to boost the CPU frequency > > if the UUF_IO flag is passed to it via cpufreq_update_util(). > > > > If that happens, the frequency is set to the maximum during > > the first update after receiving the UUF_IO flag and then the > > boost is reduced by half during each following update. > > Were these changes to schedutil part of the positive test results > mentioned in patch 5? Or are those just from intel pstate? > > I was nervous about the effect of this on power and tested a couple low > power usecases. The platform is the Hikey 96board (8 core ARM A53, > single CPUfreq domain) running AOSP Android and schedutil backported to > kernel 4.4. These tests run mp3 and mpeg4 playback for a little while, > recording total energy consumption during the test along with frequency > residency. > > As the results below show I did not measure an appreciable effect - if > anything things may be slightly better with the patches. > > The hardcoding of a non-tunable boosting scheme makes me nervous but > perhaps it could be revisited if some platform or configuration shows > a noticeable regression?
That would be my approach. :-)
I'm not a big fan of tunables in general, as there are only a few people who actually set them to anything different from the default and then they get a lot of focus (even though they are after super-corner cases sometimes).
Thanks, Rafael
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