I am experiencing some serious performance issues with my Ubuntu 12.04 setup and thus looking for the culprit by running htop alongside my usual tasks.
Aside from the usual suspects like chromium, compiz and conky, I noticed this process:
/usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch -background none
Not only is it running constantly, but it's also one of the main ressource hogs in the process list, both in regards of cpu usage as well as memory consumption.
It's the number one performance eater most of the time, only topped from time to time by an especially ressource-hungry task like flash player or the like.
Judging by the name, I'm totally unsure what it does. X and lightdm seem to indicate a relation to the gui while tcp seems network related.
My question(s): is this process supposed to run all the time? Is it legit that it uses this much ressources? Do I need it to run or is it safe to kill, if so, how to?
FYI: My system is completely up-to-date, I'm even using the xorg-edgers ppa for the very latest nvidia drivers and compiz-packages (for specific bug-related reasons).
Any suggestions would be very much appreciated.
Best Answer
This is the system graphics server and should not be killed. It converts the layout of desktop applications into low-level drawing operations on your graphics card, and routes keyboard and mouse input to the correct application that should receive them.
The reference to LightDM is that this is the first client it starts (the Ubuntu login screen); the reference to tcp is because X is designed to be network-transparent - it can work quite happily with input devices, applications and display devices all running on different computers. (I think that in Ubuntu it is configured not to accept network connections, only those coming through SSH, but may be wrong).
Check the statistics you are using are for X itself rather than X and children, since the children include all applications you run in a graphical environment. Excess resource usage by X itself is usually down to misbehaving desktop applications, but this can be very hard to debug.