On Fri, Mar 21, 2014 at 01:31:56PM +0000, Gupta, Sourab wrote: > On Fri, 2014-03-21 at 13:17 +0000, Chris Wilson wrote: > > On Fri, Mar 21, 2014 at 01:09:12PM +0000, Gupta, Sourab wrote: > > > On Fri, 2014-03-21 at 12:58 +0000, Chris Wilson wrote: > > > > On Fri, Mar 21, 2014 at 06:05:04PM +0530, sourab.gupta@xxxxxxxxx wrote: > > > > > From: Akash Goel <akash.goel@xxxxxxxxx> > > > > > > > > > > This patch Enables the bit for TLB invalidate in GFX Mode register. > > > > > > > > > > According to bspec, When enabled this bit limits the invalidation > > > > > of the TLB only to batch buffer boundaries, to pipe_control > > > > > commands which have the TLB invalidation bit set and sync flushes. > > > > > If disabled, the TLB caches are flushed for every full flush of > > > > > the pipeline. > > > > > > > > So why do we want to not disable it? > > > > -Chris > > > > > > > Hi Chris, > > > As per the description, enabling this bit will make the TLB invalidation > > > more optimal. Otherwise, TLB invalidation will happen for every full > > > pipeline flush. Thats why we are enabling this bit. > > > > You are not enabling the bit either, you simply do not disable it. > > -Chris > > > Hi Chris, > According to spec, the default value of this bit will be 1 after reset. > So, we are letting the default value remain as 1 and not disabling it. > Probably the commit message should have better reflected this as 'not > resetting the bit for TLB invalidate from its default value of 1'. > > If required, we can explicitly set the value to 1 (without assuming any > defaults). I would indeed explicitly set it according to how we've implemented TLB flushes. And you can then reference the commit that adds the pre-requisite pipe-control invalidation as if we trust our history then at some point in the past relying on an invalidate on MI_BATCH_BUFFER_START was insufficient. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
