| high system cputime % [message #22810] |
Sun, 04 November 2007 13:56  |
rickb
Messages: 368
Registered: October 2006
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Senior Member |
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Hi, this isn't an openvz specific question but I hope my friends here can help me. I am running 2.6.18 el5 openvz on an 8x 2.33 ghz opteron with 32GB mem (20GB unused by apps for page cache), and 6x sata @ software raid10 (linux md).
The system cputime % in the system seems quite high, averaging 25-35% based on dstat/vmstat/sar output.
Is there anyway to know where this cputime is going or know if there is some abuse/waste? I suspected the software raid10, because the system does heavy io constantly, but my mdX_raid10 kernel thread has only 224 minutes of cputime in 3 weeks of uptime, kjournald has 231 minutes of cputime, not a lot from my experience.
I feel a good chunk of the cpu resources are being wasted or used for purposes which are not accounted for. Is there any way to get more info?
Thanks!
Rick
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| Re: high system cputime % [message #25309 is a reply to message #22810] |
Wed, 19 December 2007 19:30  |
dev
Messages: 1693
Registered: September 2005
Location: Moscow
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Senior Member |
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if the kernel was loaded with oprofile=2 (I don't remember this exactly), then you can use oprofile tool to collect some statistics about where CPU is spent most.
also plz check softirq time reported by top.
but generally there is nothing bad is usually in system time.
For example, when you do lots of networking it takes lots of cpu system time as well. Another example: simple application, calling some syscall with wrong arguments in a loop will result in 99% CPU system time (as well as app doing good syscalls, but non-blocking and spending most of the time in kernel) 
[Updated on: Wed, 19 December 2007 19:30] Report message to a moderator |
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