radeon EXA performance questions

Michel Dänzer michel at tungstengraphics.com
Mon Aug 4 02:36:05 PDT 2008

On Fri, 2008-08-01 at 12:40 +0200, Simon Thum wrote:
> Michel Dänzer wrote:
> > 
> >> complex app takes 1/3 sec or even more). Obviously some ops are still 
> >> suboptimal. Is there interest in oprofile data?
> > 
> > Sure, though I prefer sysprof (or at least output from opreport -c as
> > well as opreport -l).
> Said, done. I didn't experience the dropout, but this profile should 
> capture what I mean. I switched eclipse, firefox and thunderbird, 
> scrolling a lot in the latter over this lovely mailing list. This is a 
> particular slow thing in EXA, roughly comparable to unpatched XAA with 
> offscreen pixmaps.

Note that every profile should be limited to a single isolated action as
much as possible in order to maximize its usefulness.

This profile shows 40% of the cycles spent copying data from video RAM
to system RAM for GetImage (Not sure what that's used for in the actions
described above...).

It also shows that you don't have the DRI enabled. The radeon driver is
known to perform much better with it enabled. Have you tried that (and
maybe also enabling Option "AccelDFS")?

> Maybe it makes sense to put a similar constraint into EXA pixmap 
> migration that my patch (previous mail) had caused in XAA? Is that 
> possible somehow?

It would be possible, but the effect may not be comparable, as EXA and
XAA use offscreen pixmaps completely differently.

Earthling Michel Dänzer           |          http://tungstengraphics.com
Libre software enthusiast         |          Debian, X and DRI developer

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