[cairo-bugs] [Bug 11529] Performance of cairo is not good without XRender extension

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Mon Jul 30 07:46:42 PDT 2007


------- Comment #17 from brian.cameron at sun.com  2007-07-30 07:46 PST -------

I should probably explain the situation about the "fixing the Xserver to use
Xrender" situation at Sun.

The main problem is that Xrender support requires support in the graphics card
driver.  On Sparc, Sun currently uses the Xsun Xserver.  With this Xserver, the
Xrender extension only works with a few graphics cards.  Also since Xrender
with Xsun is somewhat experimental it is off by default and users need to turn
it on manually to enable it.

Sun currently uses the Xorg Xserver on x86 machines, and we are migrating to
using Xorg on Sparc, but this migration will likely take a long time (probably
over a year) since Xorg currently has no drivers to support Sparc graphics
cards at all and Sun is currently working to write these drivers.  It is
expected that we won't have reasonable Xorg graphics card coverage for quite
some time.

So, until the Xorg migration happens, Sparc will continue to be 5% slower due
to lack of Xrender support.  I'm not sure yet if Sun will decide to simply deal
with low performance until the Xorg migration is done, but if there are
low-hanging performance improvements that could be made to the cairo code to
make it work better without Xrender, then I'm sure we'd be interested in
helping to code and/or test.

Your comments about what areas of the code we'd need to look into to fix this
problem is much appreciated since we are still thinking about whether we should
resource improving this performance or just deal with the low performance on
Sparc for the next year (or however long it takes for the driver team to fix
the issues).  At the moment I don't think Sun has immediate plans to release
the next version of Solaris, and if they decide to release a version before the
Xorg migration is completed, this might become a more important issue.  I know
that firefox 3.0 performance is quite bad due to lack of Xrender, for example.

Also, I wanted you to understand the situation here at Sun, so that you know
that if you see any opportunities to speed up this code, it would make us at
Sun really happy.  And also so you understand that we are working to actually
resolve the underlying problems, it just is going to take a bit of time.

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