On 17-07-20, 11:46, Vincent Guittot wrote: > On Thu, 16 Jul 2020 at 16:24, Lukasz Luba <lukasz.l...@arm.com> wrote: > > On 7/16/20 12:56 PM, Peter Zijlstra wrote: > > > Currently cpufreq_cooling appears to estimate the CPU energy usage by > > > calculating the percentage of idle time using the per-cpu cpustat stuff, > > > which is pretty horrific. > > > > Even worse, it then *samples* the *current* CPU frequency at that > > particular point in time and assumes that when the CPU wasn't idle > > during that period - it had *this* frequency... > > So there is 2 problems in the power calculation of cpufreq cooling device : > - How to get an accurate utilization level of the cpu which is what > this patch is trying to fix because using idle time is just wrong > whereas scheduler utilization is frequency invariant
Since this patch is targeted only towards fixing this particular problem, should I change something in the patch to make it acceptable ? > - How to get power estimate from this utilization level. And as you > pointed out, using the current freq which is not accurate. This should be tackled separately I believe. -- viresh
