Re: sys cpu usage

[Michael Loftis <mloftis@modwest.com>]

It really depends on what you're doing and how.  Specifics about your 
configuration can make a world of difference.  On our web servers, where 
their primary filesystem is on NFS, the NICs do UDP/TCP checksum 
offloading, and they mostly push large packets I see up to about 15% or so 
on dual core 2Ghz processors (Xeon 5130s not hyperthreaded, so four CPUs). 
But that's peak, average is more like 7-8% at around 70 hits/second, and 
we've a pretty high overhead too.  So 25%+ sounds off.

As far as finding out where it's spending time, well, there aren't many 
options there with Linux.  Solaris has dtrace, and with that you can do 
profiling. OS/X has Shark and a couple others (and they're dtrace under the 
hood).  But I've never found a good way of profiling the Linux kernel.

--On August 26, 2008 4:45:38 PM +0200 Marek Podmaka 
<marki@marki-online.net> wrote:

> Hello all,
>
> What is normal sys CPU usage in %? I have DualCore Xeon with
> hyperthreading, so 4 logical CPUs as reported by kernel (2.6.24.3),
> but the "sys" usage is about 25% (or 97% on scale when max is 400%).
> It grows proportionally with normal (user and nice) cpu usage, but
> seems too high for me. Server is running etch with php+mysql.
>
> Or is it normal? How can I see what causes it?
>
> Here is graph from munin: http://92.240.244.190/cpu-week.png
>
>
> --
>   bYE, Marki
>
>
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--
Michael Loftis
Modwest Operations Manager
Powerful, Affordable Web Hosting