Notes on fbComposite* Move To pixman?

[Daniel Stone]

On Fri, Feb 08, 2008 at 09:05:19AM -0500, Anthony L. Awtrey wrote:
> First, thanks to those that have been helping me get my head into Xorg
> code, git bisect and the rather steep learning curve to try and track
> down this regression performance issue I'm having.
> 
> I've been struggling with a performance regression between Xorg 7.0 and
> 7.2+. The suggestion from this list has been to use git bisect to try
> and figure out where the problem occurred. I have been hampered by the
> fact that the functions which appear to be key in the regression
> (fbCompositeSrc_8888RevNPx8888mmx and family) have been relocated from
> libfb.so to pixman over this period of time. This has made tracking down
> the regression more difficult since it is not a straight-forward git
> bisect issue.

So have you bisected it down to pre-merge good, merge bad?  If so, this
would suggest that its MMX handling is broken.  If not, you may just be
having issues with MTRRs or whatever (unless Xvfb exhibits the same
symptoms).

> Does anyone have design docs / notes / irc chat logs etc. on this
> change? Were there any list discussions on the impact or possible
> implications of these changes that I can read? I've searched the mailing
> list, but can't really find anything that helps me understand the nature
> of the change. Thanks!

Basically, fb/ code was copied into Cairo for use in its software
rasteriser.  libpixman was an effort to unify the fb and Cairo
codebases.  It should be more or less identical, but ...

Cheers,
Daniel
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