linux-kernel - Re: v5.8+ powersave governor breakage?

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Date:   Thu, 05 Nov 2020 15:31:19 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Mike Galbraith <efault@....de>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: v5.8+ powersave governor breakage?

On Monday, November 2, 2020 7:18:41 AM CET Mike Galbraith wrote:
> On Sun, 2020-11-01 at 17:23 +0100, Mike Galbraith wrote:
> > Greetings,
> >
> > As you can see in the data below, my i4790 box used to default to the
> > powersave governor despite CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y, and
> > disallowed switching to ondemand.
> 
> Ok, my HP lappy running master.today still defaults to powersave, with
> CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL=y, still disallows selecting
> ondemand as before, and powersave still works. IOW for lappy, it was
> business as usual, no change.

OK

> Desktop box did, it gained a working ondemand, while its previously
> working powersave went broke.

Most likely that's because it was handled by intel_pstate in the "active" mode
previously, while it is now handled by it in the "passive" mode (the modes are
described in detail in Documentation/admin-guide/pm/intel_pstate.rst) and the
default governor should be "schedutil".

Which should be slightly better from the functionality perspective.

> Box had schedutil forced upon it, but it
> seems perfectly fine with that performance wise.

Which is the expected outcome (sorry for the confusion).

Cheers!