Re: [gentoo-user] Nice level for X11

[Mick]

On Thursday 15 May 2008, Alan McKinnon wrote:
> On Thursday 15 May 2008, Abraham Gyorgy wrote:
> > I know X runs always as root. But setting the X server process'
> > priority to for example -10 makes graphical software response faster.

Setting the X server to -10 may make the X more responsive to client 
requests - theoretically that is.  However, since this is a zero sum game, 
some other processes will be short changed.  So they may (theoretically 
again) run slower.  It could well be that your KDE session becomes slower as 
a result, ha!  Anyway, just looking at the info page I read:
===================================
"  A niceness should not be confused with a scheduling priority, which
lets applications determine the order in which threads are scheduled to
run.  Unlike a priority, a niceness is merely advice to the scheduler,
which the scheduler is free to ignore."
===================================

Perhaps this is the reason why Linus has uttered his particular words of 
wisdom on this matter.

> > It works for me!! (no matter the system hangs sometimes :).
> > I think you have a fast machine, try it with a very slow computer
> > (sempron processor and radeon xpress200m+fglrx).

I have slow machine(s) and I tried your suggestion, but have not run any 
benchmarks.  I cannot sense a difference.

> You'll probably get better results with X by selecting a suitable
> process scheduler and configuring your HZ to 1000

Now, this I have noticed making a difference.  Not all schedulers are born the 
same.  I have found that (the current version of) CFQ is better than others. 

As a matter of interest, I remember reading somewhere that squeezing 1000Hz 
out of an old machine may have the opposite effect to that intended.  Is this 
pub talk, or have you experienced something that confirms this?
-- 
Regards,
Mick