Red Hat Bugzilla – Bug 246784
EXA Performance regression from FC6 to F7 affecting Firefox
Last modified: 2008-06-16 21:47:34 EDT
Description of problem:
A number of applications exhibit noticeably worse refresh performance when EXA
is enabled in Fedora 7, to the point that the applications are frustrating to
use. I am using a Radeon 9250 -- I'm not certain whether this is specific to
the ATI driver or to the Xorg package as a whole. This is a regression from
Fedora Core 6, where EXA worked fine. Fedora 7 with Fedora Core 6's xorg
packages does not exhibit the problem.
It is particularly noticeable in Firefox. Open two Firefox windows, each
showing http://www.redhat.com/. Switching between them is essentially
instantaneous on my 2.4GHz P4 under FC6 EXA or XAA or under F7 XAA. It takes
1-2 seconds to switch between them under F7 EXA, and xorg CPU usage remains at
100% for about three seconds after the window switch. Dragging any window over
the Firefox window results in extremely jerky movement and long trails over the
Unfortunately, I do not have a better way of exhibiting the problem -- all
x11perf benchmarks that I've tried show F7 EXA running more quickly than F7 XAA.
Version-Release number of selected component (if applicable):
exhibit the problem. Using the base FC6 xorg (xorg-x11-drv-ati-6.6.2-4.fc6,
Run Firefox with EXA enabled. Try switching between windows showing
http://www.redhat.com/ under EXA. Observe time taken.
Steps to Reproduce:
1. Add 'Option "AccelMethod" "EXA" to the Device section of xorg.conf.
2. Start xorg.
3. Open two overlapping Firefox windows displaying http://www.redhat.com/
4. Switch between the two. Observe time required to switch and complete redraw.
Very sluggish performance
Performance at least comparable with XAA in same release or EXA performance in
Fedora Core 6.
I am attaching the xorg logs for EXA and XAA execution -- however, the only
differences between the two are timestamps and a few memory addresses. I am
also attaching an xorg.conf file that produces the problem under FC7, does not
produce the problem under FC6, and does not produce the problem under FC7 if the
"AccelMethod" line is commented out.
Created attachment 158544 [details]
xorg log from fedora 7's xorg running with xaa acceleration
Created attachment 158545 [details]
xorg log for Fedora 7's xorg running with EXA enabled
Created attachment 158546 [details]
xorg.conf that produces slowdown in F7, but not in FC6
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