Re: sys cpu usage
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
What is normal sys CPU usage in %? I have DualCore Xeon with
hyperthreading, so 4 logical CPUs as reported by kernel (220.127.116.11),
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://18.104.22.168/cpu-week.png
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