Re: kernel go-slow

[Oleg Drokin <green@namesys.com>]

Hello!

On Thu, Feb 06, 2003 at 05:41:46PM +0100, Russell Coker wrote:

> > but there is possible situations that will not generate disk activity,
> > but may cause your system to "go-slow", if there you have some
> > unussual IO numbers while disk activity is moderate to low -
> > most likely same sweet pair.
> The problem is that sar etc product jumbled results.  Profiling the kernel may 
> help, but may also hide the error, and it's not something I can easily do.

Well, you can do it very easily.
reboot with "profile=2" kernel option.
when 100% sys cpu situation started - execute readprofile -r
when it is finished, execute readprofile -m /path/to/System.map >somefile
then sort somefile and you are done, you are now seeing where is most of the time
is spent.

> The servers are locked in a managed server room on the other side of the city 
> so seeing the blinken lights is not an option.

;)
<humour>webcam</humour>

> I've put the aa1 kernel on half the machines and now I'll wait to see what 
> happens.  If the aa1 machines don't have the problem but the others do then 
> I'll go all aa1.

Ah, if your problem was with highmem I/O not present, then that might actually help.

Bye,
    Oleg