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

[Goel, Akash]

On 8/19/2016 11:49 PM, Chris Wilson wrote:
> 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).
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.

Best regards
Akash

> -Chris
>