[Mesa-dev] [PATCH] Revert "st/vdpau: use linear layout for output surfaces"

[Michel Dänzer]

On 16/09/16 04:33 PM, Christian König wrote:
> Am 15.09.2016 um 21:43 schrieb Dave Airlie:
>> On 15 September 2016 at 17:43, Christian König
>> <deathsimple at vodafone.de> wrote:
>>> Am 15.09.2016 um 06:00 schrieb Ilia Mirkin:
>>>> On Wed, Sep 14, 2016 at 11:58 PM, Dave Airlie <airlied at gmail.com>
>>>> wrote:
>>>>> From: Dave Airlie <airlied at redhat.com>
>>>>>
>>>>> This reverts commit d180de35320eafa3df3d76f0e82b332656530126.
>>>>>
>>>>> This is a radeon specific hack that causes problems on nouveau
>>>>> when combined with the SHARED flag later. If radeonsi needs a fix
>>>>> for this, please fix it in the driver.
>>>
>>> Actually it isn't radeon specific. Using linear surfaces for this makes
>>> sense because tilling isn't beneficial and the surfaces can
>>> potentially be
>>> shared with other GPUs using the VDPAU OpenGL interop.
>> Who says tiling isn't beneficial though? Maybe on other GPUs tiling
>> might be, it
>> still seems like a radeon centric view to me.
> 
> Tiling helps with the memory throughput because it makes pixels which
> are rendered together appear near to each other in the memory layout as
> well.
> 
> Since multimedia as well as compute applications usually always render
> to the whole texture/array/matrix it usually makes no sense at all to
> enable it for those tasks.

Are you sure about that? Tiling also affects the order of memory
accesses, which could affect performance even when all pixels of a
surface are written.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer