Re: v5.8+ powersave governor breakage?

Re: v5.8+ powersave governor breakage?

[Rafael J. Wysocki]

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!

Re: v5.8+ powersave governor breakage?

[Mike Galbraith]

On Thu, 2020-11-05 at 15:31 +0100, Rafael J. Wysocki wrote:
> On Monday, November 2, 2020 7:18:41 AM CET Mike Galbraith wrote:
>
> > 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...

Perhaps the user interface should then nak switching to powersave as it
used to nak switching to ondemand?

	-Mike

Re: v5.8+ powersave governor breakage?

[Rafael J. Wysocki]

On Thursday, November 5, 2020 4:08:30 PM CET Mike Galbraith wrote:
> On Thu, 2020-11-05 at 15:31 +0100, Rafael J. Wysocki wrote:
> > On Monday, November 2, 2020 7:18:41 AM CET Mike Galbraith wrote:
> >
> > > 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...
> 
> Perhaps the user interface should then nak switching to powersave as it
> used to nak switching to ondemand?

It cannot do that if the powersave governor is configured in.

[Essentially, the problem is that the "powersave" thing advertised by
intel_pstate in the "active" mode is not really the powersave governor,
but that is a mistake made in the past and cannot be undone.  Sorry about
that.]

Re: v5.8+ powersave governor breakage?

[Mike Galbraith]

On Thu, 2020-11-05 at 19:02 +0100, Rafael J. Wysocki wrote:
> On Thursday, November 5, 2020 4:08:30 PM CET Mike Galbraith wrote:
> > On Thu, 2020-11-05 at 15:31 +0100, Rafael J. Wysocki wrote:
> > > On Monday, November 2, 2020 7:18:41 AM CET Mike Galbraith wrote:
> > >
> > > > 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...
> >
> > Perhaps the user interface should then nak switching to powersave as it
> > used to nak switching to ondemand?
>
> It cannot do that if the powersave governor is configured in.
>
> [Essentially, the problem is that the "powersave" thing advertised by
> intel_pstate in the "active" mode is not really the powersave governor,
> but that is a mistake made in the past and cannot be undone.  Sorry about
> that.]

Hohum.  A little unfortunate, but it probably only affects a few aging
boxen like mine, and I now know better that to ever again do that.