On Fri, 07 Nov 2014, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: > On Fri, Nov 07, 2014 at 11:05:05AM +0100, Daniel Vetter wrote: >> On Thu, Nov 06, 2014 at 08:40:35AM +0000, Chris Wilson wrote: >> > As obj->map_and_fenceable computation has changed to only be set when >> > the object is bound inside the global GTT (and is suitable aligned to a >> > fence region) we need to accommodate those changes when the tiling is >> > adjusted. The easiest solution is to unbind from the global GTT if we >> > are currently fenceable, but will not be after the tiling change. >> >> QA failed to supply the bisect for this regression, but most likely this >> has been introduced due to the change in handling obj->map_and_fenceable >> in >> >> commit e6a844687cf929ec053c7578d5ecc794a8a6c5cf >> Author: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> >> Date: Mon Aug 11 12:00:12 2014 +0200 >> >> drm/i915: Force CPU relocations if not GTT mapped > > I think it also took > > commit f8fcadba218fe6d23b2e353fea1cf0a4be4c9454 > Author: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Date: Fri Oct 31 13:53:52 2014 +0000 > > drm/i915: Only mark as map-and-fenceable when bound into the GGTT > > to expose the bug in testing. Valtteri confirmed this as the bisect result, and provided Tested-by on the fix. Pushed the fix to drm-intel-fixes with the commit message amended per input from Daniel and the bisect result from Valtteri; blame me for any mistakes in the commit message. Thanks for the patch and testing. BR, Jani. > >> Note that the alignment check is a vestige from our (unsuccessful) >> attempts to reduce the alignment requirements of tiled but unfenced >> buffers on gen2/3. > > Also, that was when unbinding from the GTT meant UC writes and clflushing, > so we went to great pains to avoid such. > >> That leaves the actual bug of setting map_and_fenceable to true if we're >> not bound to ggtt, which violates the change introduced in the above >> patch. Unbinding in that case really looks like the simplest and safest >> option, we have to do it anyway. >> >> If Chris agrees, please add the above analysis to the commit message when >> merging to -fixes. >> > >> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=85896 >> > Tested-by: huax.lu@xxxxxxxxx >> >> Testcase: igt/gem_concurrent_blit > Testcase: igt/gem_concurrent_blit/gttX* > > It was also only triggered by recent additions to > gem_concurrent_blit (which itself was trying to stress test our > fence-vs-GPU serialisation for testing requests - so I can claim it was > intentional!). However, it turns out to be easier to hit in practice > than in testing. :| > -Chris > > -- > Chris Wilson, Intel Open Source Technology Centre -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
