Opera and EXA: ``X Shared memory extension is not available''

Ross Vandegrift ross at kallisti.us
Mon Jun 23 13:45:07 PDT 2008

On Mon, Jun 23, 2008 at 07:11:40PM +0200, Eirik Byrkjeflot Anonsen wrote:
> Keith Packard <keithp at keithp.com> writes:
> >> I believe it was a performance hack for web pages with several layers
> >> of partial transparency.  At the time we had an evil test case which
> >> saw great speed-up with this hack.  If the shm stuff isn't available,
> >> I'm sure we'll revert to ordinary rendering (that's basically what the
> >> "error" message is about).  So nothing should break.
> >
> > Please let us know precisely what performance problem you're working
> > around so we can fix it.
> >
> Drawing lots of images with alpha-blending on top of each other was
> slow :)
> This was several years ago, and I wasn't the one doing it.  So I'm not
> too sure I remember the details correctly.

By the sound of it, I've experienced similar issues with various
flavors of driver and traced it back to multiple layers of overlapping
transparency displayed withing Mozilla.

https://bugs.freedesktop.org/show_bug.cgi?id=12671 may be relevant
(and contains a simple test case from me).
http://lists.freedesktop.org/archives/xorg/2008-March/033956.html is
the thread I started on the issue.

(Michal - I just noticed that that you responded to my update on that
bug back in March.  I'll try to have a run at getting that data this
week, as well as testing the power of 2 idea.)

Ross Vandegrift
ross at kallisti.us

"The good Christian should beware of mathematicians, and all those who
make empty prophecies. The danger already exists that the mathematicians
have made a covenant with the devil to darken the spirit and to confine
man in the bonds of Hell."
	--St. Augustine, De Genesi ad Litteram, Book II, xviii, 37

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