On 31.07.2014 18:52, Christian K?nig wrote: > Am 31.07.2014 um 11:43 schrieb Michel D?nzer: >> From: Michel D?nzer <michel.daenzer at amd.com> >> >> Signed-off-by: Michel D?nzer <michel.daenzer at amd.com> > > At least for PIPE_USAGE_STREAM buffers that's a bad idea, cause they are > used by VDPAU to read back to data to a CPU buffer and that's really > slow from VRAM.
>From src/gallium/docs/source/screen.rst: * ``PIPE_USAGE_DEFAULT``: Optimized for fast GPU access. * ``PIPE_USAGE_IMMUTABLE``: Optimized for fast GPU access and the resource is not expected to be mapped or changed (even by the GPU) after the first upload. * ``PIPE_USAGE_DYNAMIC``: Expect frequent write-only CPU access. What is uploaded is expected to be used at least several times by the GPU. * ``PIPE_USAGE_STREAM``: Expect frequent write-only CPU access. What is uploaded is expected to be used only once by the GPU. * ``PIPE_USAGE_STAGING``: Optimized for fast CPU access. That reads to me like only PIPE_USAGE_STAGING is expected to provide fast CPU reads. -- Earthling Michel D?nzer | http://www.amd.com Libre software enthusiast | Mesa and X developer
