On Thu, Apr 14, 2016 at 3:29 AM, Michel Dänzer <[email protected]> wrote: > 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 <[email protected]> >>> 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.
We need to make sure the buffers end up in WC GTT. The cache snoops for coherent GTT reduce performance. Alex > > 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 > _______________________________________________ > mesa-dev mailing list > [email protected] > https://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/mesa-dev
