Red Hat Bugzilla – Bug 501182
Very slow trapezoid rasterization
Last modified: 2009-06-12 19:36:53 EDT
Description of problem:
All applications which render a lot of trapezoids are quite slow when using UXA+KMS. I guess this is caused by the fix for bug 490839.
Version-Release number of selected component (if applicable):
Always. Some applications suffer less, some a lot (OpenOffice 3.1, FireFox for some pages).
Steps to Reproduce:
1. Open an openoffice(3.1)-document
1.2. Move e.g. a chart arround
2. Open a trapezoid-heavy page in firefox.
Very slow rendering of trapezoids, profilers show almost all time spent in pixman_rasterize_edges.
Because the amount of trapezoids is the same for EXA/XAA/UXA the only conclusion I can make is that memory access is uncached and therefor slowing that code down.
At least as fast as EXA
I reported this bug already upstream, however I am not sure its really their fault:
Created attachment 344335 [details]
sysprof profile of OOo moving simple chart arround
I did some firefox performance measurements using Trender.
XAA/EXA was on Fedora8 with intel-2.2.1
UXA was on Fedora 10 with KMS
The steady slowdown is concerning :-/
Created attachment 344509 [details]
FireFox performance comparison of XAA, EXA and UXA
This bug appears to have been reported against 'rawhide' during the Fedora 11 development cycle.
Changing version to '11'.
More information and reason for this action is here:
This is an intel-bug, caused by rendering trapezoid to pixmaps instead of system memory. Should be fixed in 2.8 (pre releases).