Red Hat Bugzilla – Bug 562255
Storm of EDID probe notifications ties up Xorg+udev, slows machine to a crawl
Last modified: 2010-02-17 10:53:41 EST
Created attachment 389160 [details]
PCI description of machine as reported by lspci
Description of problem:
With distro kernel and KMS enabled (in default configuration), sometimes the graphics output will slow down and graphic updates become jerky and stuttering. This happened during the very F12 installation process on this machine, and continues with the most recent kernel/udev/Xorg versions as detailed below.
When this problem happens, a console login shows Xorg and udev taking lots of CPU time. The udev daemon, in particular, takes up 20% of CPU with priority -2 or -4, which ties up the rest of the processes. Also, /var/log/Xorg.0.log starts filling up with repetitive messages about EDID probes. My display is a LCD one at 1440x900 with a VGA connector, but I am not fiddling at all with my cables, or with the (currently unused) digital output, so there is no excuse for repeated EDID messages.
I found that udev has a queue at /dev/.udev/queue.bin. On normal operation, this file is at most a few kb long. During one of these storms, the file grows alarmingly large (got a sample of almost 600 Kb).
With the current kernel, I might have a few hours of normal operation, and then the graphics slow down when moving windows and compiz enabled. By running a tail -f /var/log/Xorg.0.log I see that moving a big window around results in a bunch of EDID probe messages being sent to the log file (why???). With earlier kernels I might find the machine slows down without any user interaction whatsoever.
The only workaround I have found is to kill -9 udevd from a text console. After a few seconds the machine becomes responsive again.
Version-Release number of selected component (if applicable):
Sometimes (might take a while of normal desktop use to manifest).
Steps to Reproduce:
udevd and Xorg tie up CPU time and graphics output becomes jerky.
No CPU tying.
Smolt profile of machine at:
Created attachment 389161 [details]
dmesg output on affected kernel
Created attachment 389162 [details]
Copy of /dev/.udev/queue.bin during probe storm
Hexdump of this file shows copies of the same event being sent over and over.
Created attachment 389163 [details]
Xorg log during episode of probe storm
I am currently running vanilla linux kernel 2.6.33-rc6 to check whether this issue appears in upstream kernel. So far I have seen no slowdowns.
It seems to be in Ubuntu as well http://ubuntuforums.org/showthread.php?p=8775007
If you are using Intel video drivers, this is almost certainly a duplicate of https://bugzilla.redhat.com/show_bug.cgi?id=523646
I need to leave my mother with a stable working system before I go overseas, so I don't really want to play with non-standard kernels.
*** This bug has been marked as a duplicate of bug 523646 ***