glamor acceleration performance on radeonsi

Michel Dänzer michel at
Thu Nov 15 02:18:40 PST 2012

On Don, 2012-11-15 at 01:00 +0400, Igor Vagulin wrote: 
> I tried glamor acceleration on xf86-video-ati-7.0 & mesa-9.0 &
> kernel-3.6.6.

Note that the radeonsi driver in Mesa 9.0 is very immature. Right now
you should always use latest Git for radeonsi.

> I didn't see any performance improvements in comparison with
> modesetting and catch 2 noticeable performance regressions:
> - gtkperf bench times worse with glamor enabled (attached)
> - firefox/thunderbird window resize seriously lags

This is expected at this point. Because the radeonsi shader compiler
can't quite handle some of glamor's shaders yet, so far only DRI2 buffer
copies are accelerated (so GL / vdpau apps can work at full
performance). Everything else is rendered in software to VRAM directly,
which is slower than the shadow framebuffer used by
xf86-video-modesetting (or -ati with acceleration disabled).

We are getting close to making the radeonsi shader compiler handle all
the glamor shaders (only support for loops seems missing), so hopefully
we can enable full 2D acceleration on SI soon.

Earthling Michel Dänzer           |         
Libre software enthusiast         |          Debian, X and DRI developer

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