radeon EXA performance questions

Simon Thum simon.thum at gmx.de
Tue Aug 5 07:56:47 PDT 2008

Owen Taylor wrote:
> On Mon, 2008-08-04 at 21:40 +0200, Simon Thum wrote:

> Not completely sure what you mean by locks. Typically "good performance"
> with XAA mean that you've set XaaNoOffscreenPixmaps, and are using pure
> software rendering; pure software rendering is much faster than badly
> accelerated rendering.

It was just a guess; however I did not disable OSPM with XAA, but instead
patched it to only handle very small pixmaps. This gave me good FF/TB perf
while maintaining console performance (which drops with OSPM disabled).

> Extensive use of GetImage will thus reduce parallelism between the CPU
> and the GPU.
Thanks for the explanation! That was my initial assumption, that XAA would
'just read' and not care about proper locking. However, I re-did the three
intermixed cases separately, and all show extensive libc (i.e. memcpy)
and a minor ExaWaitSync. So DRI will be the next thing to check.

More information about the xorg mailing list