oprofiling Xorg
Dennis Jacobfeuerborn
d.jacobfeuerborn at conversis.de
Thu Dec 8 18:13:10 PST 2005
Hi,
I've been playing with oprofile in order to find out why Xorg seems to be
so slow with my r300 based Radeon 9500pro. I'm doing the profiling on an
up-to-date Fedora Core Rawhide system with modular x installed (with the
Composite extension enabled) and this is what the device section in
xorg.conf looks like:
Section "Device"
Identifier "Videocard0"
Driver "radeon"
VendorName "Videocard vendor"
BoardName "ATI Radeon 9500 Pro"
Option "AccelMethod" "exa"
EndSection
For the test I simply opened some applications on the desktop, started
oprofile and then moved the Firefox window back and forth across the
desktop for a few seconds. Here what a simple "opreport
--exclude-dependent" says:
CPU: CPU with timer interrupt, speed 0 MHz (estimated)
Profiling through timer interrupt
TIMER:0|
samples| %|
------------------
2126 34.0106 libfb.so
2071 33.1307 vmlinux-2.6.14-1.1726_FC5
311 4.9752 Xorg
281 4.4953 libc-2.3.90.so
270 4.3193 radeon
161 2.5756 libgdk-x11-2.0.so.0.800.8
151 2.4156 libglib-2.0.so.0.900.0
150 2.3996 libgobject-2.0.so.0.900.0
127 2.0317 libcairo.so.2.2.3
127 2.0317 libgdk_pixbuf-2.0.so.0.800.8
63 1.0078 libgtk-x11-2.0.so.0.800.8
59 0.9438 libpthread-2.3.90.so
...
Seeing that libfb.so seems to swallow most of the time I did a "opreport -l
/usr/lib/xorg/modules/libfb.so" with the following result:
CPU: CPU with timer interrupt, speed 0 MHz (estimated)
Profiling through timer interrupt
samples % symbol name
1519 71.4487 fbCopyAreammx
195 9.1722 fbRasterizeEdges
143 6.7262 fbSolid
105 4.9389 fbSolidFillmmx
85 3.9981 fbCompositeSolidMask_nx8x8888mmx
21 0.9878 fbCompositeSrcAdd_8000x8000mmx
14 0.6585 fbCompositeSrc_8888x8888mmx
10 0.4704 fbComposite
...
Is Xorg supposed to use fbCopyAreammx instead of some hardware assisted
blitting function with my configuration? I'm installing the kernel
debuginfo package right now to see where the other 33% of performance are
going but I wonder if there is something about my configuration that slows
things down so significantly.
Regards,
Dennis
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