Comment 50 for bug 252094

On Fri, 2008-11-07 at 11:12 -0800, Dan Elder wrote:
> The issue I'm seeing with EXA is that window drawing (2d) performance is very
> slow to the point where it feels like I'm using a very old system with a vesa
> driver. Minimizing, maximizing, or dragging windows around is laggy. Not
> unusable slow, but probably a good 10 times slower than with XAA.

Thanks. There's a little more detail in there which is useful.

What we really want to figure out next is what operation is being asked
for here, which gets us to...

> I don't have
> the desktop effects enabled (although I believe AIGLX is turned on).

The real question here is whether or not there's a compositing manager
running. One some distributions, (such as Fedora, I believe), by default
there's no compositing manager running, (just metacity without its
builting compositing support), and then if you turn on "desktop effects"
it runs compiz. That may or may not be the same with OpenSUSE.

But better than just knowing "yes, there's a compositing manager
running" would be to find a benchmark score that actually changes in a
manner that correlates with the behavior you are seeing.

For example, if the slow operation here is straight blitting, (window
copying without blending), then you could run something like:

 x11perf -copypixwin500

or so under both XAA and EXA to see if the scores change in a manner
similar to your bug. When you find an x11perf test case that changes
with XAA and EXA then we've hit the jackpot and debugging gets *much*
easier from there.

I'm suspecting that compositing is actually happening here, not just
copying. In old versions of x11perf there weren't any compositing tests.
If you've got a sufficiently new x11perf then you can do something like:

 x11perf -comppixwin500

I'm not 100% sure that that test is doing something entirely useful, (it
does seem to call the right blending functions but with apparently no
alpha channels).

Anyway, any details you might be able to provide would be great.

-Carl