Re: high system cpu usage, no culprit in top

[Justin Guerin <jguerin@cso.atmel.com>]

On Wednesday 07 April 2004 11:58, Brent Miller wrote:
> Justin Guerin wrote:
> >My CPU is 100% utilized, but no processes seem to be using the CPU.  I
> > can't seem to figure out what's causing the load.  I know that
> > something is, though, because xscreensaver is running very slow.
>
> Some daemons (mysql comes to mind) won't show up under top, but of
> course continue to use resources. I _think_ this is because of the way
> they do threading---If you do a top or ps -A you'll only get the parent
> processes and not the children (who are actually using the cpu.)
>
> I remember that there is a command that shows you what processes are
> running that are not showing up under ps, but I cannot think of it at
> the moment. You can always compare the PID's from ps -A against
> /proc/[0-9]* to find the culprit though.
>
> HTH,
> Brent
Thanks for the input.  I wasn't able to decode /proc/[0-9]*/stat to the 
system CPU load, though.  I think I would have to check the stime jiffy 
count for all processes, then see who had the largest share, but it's hard 
to do that real-time _and_ compare to top's output so I know I'm doing it 
right.

In any case, I noticed that X was using a lot of CPU system time, even 
though it had been reniced (manually).  So I decided to start there.  I 
restarted X, and it hasn't happened since.  This is the first time I 
restarted X since I reconfigured it to run a 0 nice, not -10.  It seems 
that manually renicing the running application doesn't have the same effect 
as editing the config and restarting.

I guess there's some use for rebooting your computer ouside of a kernel 
upgrade or a bootloader splash screen change (even though I still haven't 
done that: I only restarted X ;-)

Justin