Re: [PATCH RFC v4] cpufreq: schedutil: Make iowait boost more energy efficient

From: Peter Zijlstra
Date: Wed Jul 12 2017 - 05:37:25 EST

On Wed, Jul 12, 2017 at 10:30:35AM +0530, Viresh Kumar wrote:
> On 11-07-17, 07:14, Joel Fernandes wrote:

> > Another approach than setting min in sugov_set_iowait_boost, is, since
> > we have already retrieved the current util, we can check if flags ==
> > SCHED_CPUFREQ_IOWAIT, then set initial the iowait_boost such that
> > (iowait_boost / iowait_boost_max) is aleast equal to (util / max) or
> > iowait_boost_min, which ever is lower.
> So my concerns weren't only about the initial min value, but also that you
> reduce the freq from sugov_set_iowait_boost(). We can discuss what the ideal
> value to start with can be.

I'm not sure I see that. He only mucks with iowait_boost, not the actual
frequency afaict.

And sugov_iowait_boost() picks the highest of util vs iowait_boost,
which wasn't changed.

Or am I completely missing something? (that code is a bit hard to