Re: [RFC PATCH 0/7] sched: cpufreq: Remove magic margins

From: Lukasz Luba
Date: Thu Sep 07 2023 - 13:33:33 EST




On 9/7/23 14:26, Peter Zijlstra wrote:
On Wed, Sep 06, 2023 at 10:18:50PM +0100, Qais Yousef wrote:

This is probably controversial statement. But I am not in favour of util_est.
I need to collect the data, but I think we're better with 16ms PELT HALFLIFE as
default instead. But I will need to do a separate investigation on that.

I think util_est makes perfect sense, where PELT has to fundamentally
decay non-running / non-runnable tasks in order to provide a temporal
average, DVFS might be best served with a termporal max filter.



Since we are here...
Would you allow to have a configuration for
the util_est shifter: UTIL_EST_WEIGHT_SHIFT ?

I've found other values than '2' better in some scenarios. That helps
to prevent a big task to 'down' migrate from a Big CPU (1024) to some
Mid CPU (~500-700 capacity) or even Little (~120-300).