Re: PREEMPT_RT vs i915

Mike Galbraith
2025-07-10T04:53:30Z

On Wed, 2025-07-09 at 23:09 +0300, Ville Syrjälä wrote:
> On Wed, Jul 09, 2025 at 09:44:43PM +0200, Sebastian Andrzej Siewior wrote:
> > On 2025-07-09 20:30:26 [+0300], Ville Syrjälä wrote:
> > > >
> > > > It seems like the critical uncore lock is currently held in a lot of
> > > > places and potentially for a long time.
> > >
> > > It shouldn't be held for that long. I think it should just be
> > > a raw spinlock.
> >
> > What about I resubmit the series and we look again? I don't think the
> > lock should be made raw just to be done with it.
>
> Until someone actually does the work to confirm the thing is working
> reliably there's no point in posting anything.

What does that entail?

My little i915 equipped lappy seems perfectly happy with the latest RT
kernel+DEBUG_ATOMIC_SLEEP. The thing is an awful RT platform, but as
far as display handling goes go, it does fine at browsing as long as
you're not picky about hires frame drop (not RT related), nor does the
not very impressive looking rendering glmark2 does trigger splats.

WRT reliability, it's primary mission is to be a console, can and does
idle for days on end without dying of boredom, waking for an occasional
ssh session or OS update.. so.. check? :)

-Mike