On Sat, Aug 20, 2016 at 12:14:46PM +0530, Goel, Akash wrote: > > > On 8/19/2016 11:49 PM, Chris Wilson wrote: > >On Fri, Aug 19, 2016 at 02:13:16PM +0530, akash.goel@xxxxxxxxx wrote: > >>From: Akash Goel <akash.goel@xxxxxxxxx> > >> > >>In order to have fast reads from the GuC log buffer, used SSE4.1 movntdqa > >>based memcpy function i915_memcpy_from_wc. > >>GuC log buffer has a WC type vmalloc mapping and copying using movntqda > >>from WC type memory is almost as fast as reading from WB memory. > >>This will further reduce the log buffer sampling time, so is needed dearly > >>to deal with the flush interrupt storm when GuC is generating logs at a > >>very high rate. > >>Ideally SSE 4.1 should be present on all chipsets supporting GuC based > >>submisssions, but if not then logging will not be enabled. > >> > >>v2: Rebase. > >> > >>Suggested-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > >>Signed-off-by: Akash Goel <akash.goel@xxxxxxxxx> > >>Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > > > >Should be squashed with patch 16 (use MAP_WC). > Fine will squash, but please could you tell that what issue could be > there with 2 patches being separate. Either both will be merged or > none of them will be merged. Further reflection is that the initial patch to map the log should be with MAP_WC. Correctness first, then the performance patch. As it stands, the story being told is: 1. Enable readback. 2. Oops, that isn't correct, better map it WC 3. Oops, that is too slow, better use movntqa. A better story is 1. Enable readback, enforcing coherency. 2. Accelerate readback for !llc. -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
