Comment 23 for bug 449196

I am also experiencing the high cpu usage by Xorg process with the following scenario:

1. Two X sessions with two users (A and B) logged in
2. High cpu usage is triggered on user A's Xorg in 10 minutes after switching to user B
3. When switching back to user A, the cpu usage drops down
4. After 10 minutes user B's Xorg starts to use full cpu

This is a laptop with core duo. I suspect that the trigger for high cpu usage is the timer for powering off or dimming the display or some other powerdevil setting.

strace for the high cpu using Xorg gives something like this:

setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 0}}, NULL) = 0
clock_gettime(CLOCK_MONOTONIC, {94512, 5192525}) = 0
select(256, [1 3 7 9 11 12 13 19 20 21 22 23 24 25 26 27 28 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46], NULL, NULL, {0, 0}) = 1 (in [46], left {0, 0})
clock_gettime(CLOCK_MONOTONIC, {94512, 5332906}) = 0
setitimer(ITIMER_REAL, {it_interval={0, 20000}, it_value={0, 20000}}, NULL) = 0
read(46, "5\30\4\0Z\241\201\3\217\2\201\3j\0\24\0005\30\4\0[\241\201\3\217\2\201\3j\0\24\0"..., 4184) = 976
ioctl(8, 0x400c645f, 0xbf83a814) = 0
...
...
clock_gettime(CLOCK_MONOTONIC, {94512, 7638436}) = 0
ioctl(8, 0x400c645f, 0xbf839424) = 0
...
...