On Mon, May 11, 2015 at 12:34:37PM +0200, Daniel Vetter wrote: > On Mon, May 11, 2015 at 08:51:36AM +0100, Chris Wilson wrote: > > With the advent of mmap(wc), we have a path to write directly into > > active GPU buffers. When combined with async updates (i.e. avoiding the > > explicit domain management along with the memory barriers and GPU > > stalls) we start to see the GPU read the wrong values from memory - i.e. > > we have insufficient memory barriers along the execbuffer path. Writes > > through the GTT should have been naturally serialised with execution > > through the GTT as well and so the impact only seems to be from the WC > > paths. > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Cc: Akash Goel <akash.goel@xxxxxxxxx> > > Cc: stable@xxxxxxxxxxxxxxx > > Do we have a nasty igt for this? Bugzilla? I've added igt/gem_streaming_writes. That wmb() is not enough for !llc. Since the wmb() made piglit happy it is quite possible I haven't hit the same path exactly, but it's going to take some investigation to see if igt/gem_streaming_writes can possibly work on !llc. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
