Re: Frame buffer access performance

On Fri, Aug 05, 2016 at 04:35:25AM +0200, Enrico Weigelt, metux IT consult wrote:

Hi folks,

when putting pixels into an DRM framebuffer, should I do that in bursts/blocks instead of byte-per-byte ? (eg. explicitly using aligned 32bit ops).

There's a driver cap DRM_CAP_DUMB_PREFER_SHADOW for this. If set, render into a shadow buffer and copy over in bursts, otherwise you can assume that the memory is fully cpu cached and fast with random access. Note that this is just for dumb buffers, which are explicitly not meant as the fastest memory, but the most convenient (i.e. untiled). -Daniel