On Thu, Jul 10, 2025 at 06:52:58AM +0200, Mike Galbraith wrote: > 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? Basic testing would be something like this: - enable CONFIG_DRM_I915_DEBUG_VBLANK_EVADE - set i915.enable_dsb=0 to make sure everything takes the mmio path - stress the heck out of it and make sure the histogram doesn't look significantly worse than on !RT (kms_atomic_transition --extended might take care of the display side here, but it should probably be accompanied with some horrendous system loads which is a less well defined part) - ideally do that on a potato (some VLV/CHV (Atom) thing would probably be a good candidate) - repeat with lockdep enabled to make everything even harder -- Ville Syrjälä Intel
