[cod] Disapointed - MAYDAY read this

Dave Whitla dave.whitla at ocean.net.au
Sat Dec 13 22:26:38 EST 2003


On Wed, 26 Nov 2003 12:11 pm, Dave Whitla wrote:
> On Wed, 26 Nov 2003 12:02 pm, Mike wrote:
> > I take it you think we are server newbies? :)
> > I know maydays server is fast. My own server is a P4 2.4Ghz, 30Gb hdd,
> > 1024Mb pc2100 ram and a geforce 3. So I hardly think you can compare your
> > system to that? ;)
> >
> > With a system like this, it SHOULD work. :/
>
> Post output of 'ps aux' (execute this as root) as a start.
> 'top' output during a lag would be good if you could catch it ;-).
> Also can you post output of 'dpkg -l libc6'.  It may be useful to Ryan.
>
> Dave

Just had a thought after some major irritation with my Linux box at home.

I think I have found the ultimate source of your problem if:

* you are using an Intel P4 processor with hyper-threading enabled
* you are using kernel 2.4.20 - with SMP compiled in (to make use of the HT 
capability of the CPU)

Every so often ksoftirqd_CPU0 will tie up the CPU at almost 100% utilisation - 
apparently stuck in some kind of loop - trying to schedule maybe. When this 
happens every other process gets put on hold for a few seconds.  If you don't 
use X on your Linux box you probably wouldn't notice it except as the lag you 
are experiencing.

Revert to non-SMP kernel and problem disappears.

Checking now to see if this is documented and fixed in a later kernel.

Dave 






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