[Mesa-dev] Mesa (master): 29 new commits

Michel Dänzer michel at daenzer.net
Thu Apr 14 07:29:29 UTC 2016

On 14.04.2016 11:37, Michel Dänzer wrote:
> On 12.04.2016 21:33, Marek =?UNKNOWN?B?T2zFocOhaw==?= wrote:
>> URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=5a4b74d1ba2c156766a7a5dbfef099c7db5d6694
>> Author: Marek Olšák <marek.olsak at amd.com>
>> Date:   Mon Apr 11 19:56:07 2016 +0200
>>     gallium/radeon: relax requirements on VRAM placements on APUs
> This change caused a bunch of ARB_shader_load_image_store piglit tests
> to fail on my Kaveri, see some examples below. The incorrect values
> seem consistent.
> I suppose some buffers end up in GTT instead of VRAM with this
> change, but I'm not sure how that could cause problems. Any ideas?

Also, with the code modified to use GTT only for everything but
(potential) scanout buffers, the performance of Unigine Valley and the
Unreal Engine 4 Elemental demo is reduced by about 30%. So the premise
that GTT is about as fast as VRAM doesn't seem to hold true in practice
(at least with Kaveri and presumably other (pre-)CIK APUs; maybe it's
better with Carrizo and newer), which means that this change may cause
performance of long-running processes to drop significantly over time.

Given all these issues, I'm afraid it may be better to revert this
change for now, until we have a better plan for dealing with this.

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

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