On 30-07-20, 12:16, Lukasz Luba wrote: > Hi Viresh, > > On 7/30/20 7:24 AM, Viresh Kumar wrote: > > 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. > > > > I don't think that these two are separate. Furthermore, I think we > would need this kind of information also in future in the powercap. > I've discussed with Daniel this possible scenario. > > We have a vendor who presented issue with the IPA input power and > pointed out these issues. Unfortunately, I don't have this vendor > phone but I assume it can last a few minutes without changing the > max allowed OPP. Based on their plots the frequency driven by the > governor is changing, also the idles are present during the IPA period. > > Please give me a few days, because I am also plumbing these stuff > and would like to present it. These two interfaces: involving cpufreq > driver or fallback mode for utilization and EM.
Its been almost 3 months, do we have any update for this? We really would like to get this patchset merged in some form as it provides a simple update and I think more work can be done by anyone over it in future. -- viresh
