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Re: [LUG] High system use, low load average

 

On 8/15/06, Paul Weaver <iso@xxxxxxxxxxxx> wrote:

> However top, (and snmp), report an insanely high cpu use in the "system"
> catagory -- 99% on CPU1, 90% on CPU2 (and 10% for top).

Probably not much help but on 2.4 kernels doesn't waiting IO show up
as system usage but on 2.6 this as a wait IO section in top etc. Is
the system waiting for disk IO and that is the problem?

>
> The "problem machine" is a vanilla 2.4.32 kernel, however the interupt
> timer has been increased to 1024Hz when I compiled it (specific need for the
> software).
>

The timer tick interrupt has caused flame wars before from what I have
read, it appears that in many cases you can do without it by
substituting any call for jiffies to read the RTC instead, apparently
its a problem for large number of virtual machines as the timer ticks
use up all the processing power!. Don' t think this is anything to do
with your problem however but this might:-

It also appears that process accounting under heavy load is inaccurate:-

http://www-128.ibm.com/developerworks/linux/linux390/perf/tuning_rec_accounting.html

might be related?

Also ever tried 2.6.X on these systems with a totally different (and a
few build options) for scheduling routines

Regards

-- 
Robin Cornelius
http://www.byteme.org.uk

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