Why does fglrx run two X servers?

[FlyingFlo]

Hi!

I'm running fglrx (8.7 package) on ubuntu 8.04 32-bit with a Radeon HD3870 card and two displays connected via DVI.

Recently i noticed that there are two X servers running, although i do not use any multiuser features, btw switching the user causes the whole system to freeze.

One X server starts the other, they use exactly the same amount of memory, but one of them is sleeping always (doesn't collect any cpu time).

$ ps aux | grep X
root      6365  2.2  9.6 214248 200464 tty7    Ss+  12:09   1:43 /usr/bin/X :0 -br -audit 0 -auth /var/lib/gdm/:0.Xauth vt7
root      6472  0.0  9.6 214248 200464 tty7    S+   12:09   0:00 /usr/bin/X :0 -br -audit 0 -auth /var/lib/gdm/:0.Xauth vt7

This is also the case if the second display is not used. It seems to be caused by fglrx, because on a similar machine with nvidia card, i only have one X running.

I also tried killing the passive X, it just has no effect!
If i can save a few hundreds of MB of RAM by not running a senseless second X, it would be nice.

Would be interesting to know what it's all about.
Is it the same on your machine?
Can anyone explain that?

Flo

[bridgman]

I think this is two threads, not two separate processes (so only one of them is really using memory). Mtippett has explained this in another thread somewhere.

[FlyingFlo]

Thanks!

Unfortunately I didn't find that thread
http://www.phoronix.com/forums/showthread.php?t=10811
before posting mine.
It's exactly the same issue.
It seems that the clone() system call (man page) allows to processes to share the same memory space but have different PIDs then.

Regards,
Flo