> >Im looking into why the Xserver starts with niceness -1 when started as root.
> >Ive tracked the occurance down to these lines in xinit.c 
> >#ifdef PRIO_PROCESS
> >                setpriority( PRIO_PROCESS, serverpid, -1 );
> >#endif

> >basically the setpriority() call is made whenever the Xserver is initialised.
> >If this is done by a normal user niceness will become 0 as a normal user
> >cannot set niceness below 0. But as root, well as you can see -1 ...

> GUI responsiveness is critically important.  Nothing makes a system feel
> sluggish more than poor mouse response, even if everything else is
> blazingly fast.

Except that running the X server w/ a different priority than local
clients is not a good idea... Exactly how bad idea this is depends
on the scheduler (if the -1 difference in priority does not mean much
then the effects won't be as visible), but you should be able to see
for yourself by eg running an xterm and doing something like "ls -l"
on a large directory a few times, with the xterm at 1) lower, 2) higher
and 3) equal priority to the server. Last time i tried that was a quite
a few years ago, faster machines could make it less noticable (SMP hides
the problem too), but basically if you run the client at lower priority
(eg because you set the server to -1) it will appear as if most X calls
were followed by an XSync() (terminal will scroll line-by-line, apps
will draw their widgets synchronously etc). I certainly wouldn't use
the term "blazingly fast" to describe such a system...
(running apps at higher prio has a different effect; this can really
make the system feel sluggish, while visually "cleaner" - less
incremental drawing, terminal scrolls page-by-page etc)

I doubt the -1 difference makes things as bad as the extremes described
above, but i don't believe it actually improves things, and the effects
are most likely still there.

artur
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