kdm.log and Xorg.0.log files become huge

[Tim Holy]

Binary package hint: xorg

I'm running Intrepid/Kubuntu. I'm hoping to report a couple of X.org bugs, but before doing that I checked the log files. They were HUGE:
-rw-r--r-- 1 root root 28685489 2008-11-02 05:07 Xorg.0.log
-rw-r--r-- 1 root root 91736609 2008-11-01 06:13 Xorg.0.log.old
-rw-r--r-- 1 root root 97730 2008-07-25 09:26 Xorg.10.log
-rw-r--r-- 1 root root 97730 2008-07-25 09:26 Xorg.10.log.old
-rw-r--r-- 1 root root 51670 2007-04-14 20:41 Xorg.1.log
-rw-r--r-- 1 root root 61263 2006-12-21 13:09 Xorg.1.log.old
-rw-r--r-- 1 root root 51159 2008-05-16 09:16 Xorg.9.log
-rw-r--r-- 1 root root 46080 2008-05-16 09:15 Xorg.9.log.old
-rw-r--r-- 1 root root 84244 2008-10-20 04:47 Xorg.failsafe.log
-rw-r--r-- 1 root root 84244 2008-10-20 04:47 Xorg.failsafe.log.old

And kdm was even worse (almost 1 gigabyte in 48 hours):
-rw-r--r-- 1 root root 829730938 2008-11-02 05:07 kdm.log
-rw-r--r-- 1 root root 387159 2008-10-31 04:58 kdm.log.1
-rw-r--r-- 1 root root 2678 2008-10-30 05:37 kdm.log.2.gz
-rw-r--r-- 1 root root 2474 2008-10-29 05:27 kdm.log.3.gz
-rw-r--r-- 1 root root 2839 2008-10-28 02:33 kdm.log.4.gz
-rw-r--r-- 1 root root 3777 2008-10-27 08:18 kdm.log.5.gz
-rw-r--r-- 1 root root 2910 2008-10-26 08:15 kdm.log.6.gz
-rw-r--r-- 1 root root 1852 2008-10-25 16:02 kdm.log.7.gz

I suspect the really rapid growth in these files coincided with me turning on desktop effects. But, I notice they grow pretty quickly even with effects off.

To avoid sending you enormous files, here is what I did: I turned off desktop effects, rebooted into "recovery mode", deleted the huge log files from a root console, and continued with a normal (graphical) boot. I then ran "apport-cli -f --package xorg" very shortly after boot (probably within 1 minute). My file sizes at the moment (some minutes after running apport-cli, and perhaps only ten minutes after booting) are now:
-rw-r--r-- 1 root root 8459 2008-11-02 05:53 kdm.log
-rw-r--r-- 1 root root 265354 2008-11-02 05:53 Xorg.0.log

kdm.log is filling with this message:
Dac detection success
in RADEONProbeOutputModes
invalid output device for dac detection

It may also be worth noting that the "Detect RANDR (monitor) changes" service is running.

By 24 minutes uptime, the file sizes are:
tim@diva:/var/log$ ls -l kdm.log Xorg.0.log
-rw-r--r-- 1 root root 11979 2008-11-02 05:59 kdm.log
-rw-r--r-- 1 root root 398994 2008-11-02 05:59 Xorg.0.log

I'll follow this message with these two files attached after 1 minute of running with desktop effects turned on.

ProblemType: Bug
Architecture: i386
DistroRelease: Ubuntu 8.10
Package: xorg 1:7.4~5ubuntu3
ProcEnviron:
 SHELL=/bin/bash
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/bin/X11:/usr/games:/home/username/bin:/home/username/bin
 LANG=en_US.UTF-8
 LANGUAGE=en_US
ProcVersion: Linux version 2.6.27-7-generic (buildd@palmer) (gcc version 4.3.2 (Ubuntu 4.3.2-1ubuntu11) ) #1 SMP Thu Oct 30 04:18:38 UTC 2008

SourcePackage: xorg
Uname: Linux 2.6.27-7-generic i686
xkbcomp:

[Tim Holy (holy-wustl)]

Well, having turned desktop effects on, I'm not sure the growth is any faster. But here's kdm.log

[Tim Holy (holy-wustl)]

...and here's Xorg.0.log

[Tim Holy (holy-wustl)]

I started looking at the pattern of growth, and noticed that they seemed to both grow in parallel every 10 seconds or so (and would be stable in between). So I suspected it was the "Detect RANDR (monitor) changes" setting. So, I experimentally turned that off, and the log files are not growing anymore.

Incidentally, one of the bugs I was hoping to report (before deciding that you probably wouldn't want a 1Gb file...) seems to have been covered in bugs #278471 and #279719. The blinking only happens with one particular external projector I've tested, it doesn't happen with my laptop's screen or with the external monitor I usually use at work. I'm not connected to either of those right now, but I can capture log files when connected if it would be helpful.

[Bryce Harrington (bryce)]

Yes, it looks like a client application is doing monitor probing using an expensive Xrandr call. I gather that "Detect RANDR (monitor) changes" service is something provided by kubuntu. Not sure what product that belongs to; filing against kubuntu-meta for now, but if you know more specifically what component is doing this probing, please update the package accordingly.