[Intel-gfx] [PATCH 17/19] drm/i915: Use SSE4.1 movntdqa based memcpy for sampling GuC log buffer

[Chris Wilson]

On Fri, Aug 19, 2016 at 02:13:16PM +0530, akash.goel at intel.com wrote:
> From: Akash Goel <akash.goel at intel.com>
> 
> 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 at chris-wilson.co.uk>
> Signed-off-by: Akash Goel <akash.goel at intel.com>
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Should be squashed with patch 16 (use MAP_WC).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre