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:

quoted

From: Rafael J. Wysocki <redacted>

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