Kain, Becki (B.) wrote:
I care because I'm trying to figure out what threads of certain processes are continuing to run at 99% of a cpu. I'd like to know what the system is considering "system space" in top's calculation of system space.
when you run top, the default configuration is to order processes by CPU time during the latest observation time (1 second by default). and it's not system SPACE, it's the amount of TIME spent executing kernel code (as opposed to non-kernal code which is "user"
I'm trying to solve a reoccurring pegging of the cpu's issue. If there is another set of commands that I should be using, please let me know
Pegging the CPU's is not necessarily a problem. It just means that the current mix of processes is CPU bound (which is normally a GOOD thing!) Idle time only occurs when an I/O-bound process is waiting for I/O to complete)....and that's wasted CPU cycles. A pegged CPU means that the CPU is actually working to its full potential. The only time it's an issue is if the computer is used interactively (i.e. not a compute server, such as running FEA or CFD jobs) ***AND*** the interactive interface is too sluggish. A much more significant problem is one that we had when I was at KMart headquarters about 10 years ago. New distribution-center inventory/management system...on an Informix Database, and 4-CPU HP 9000 series machine---Running VERY slowly. Idle time was about 95%. Against my advice, management threw in 4 MORE CPUS...now we had an 8 CPU box running at 97.5% idle.... The problem turned out to be that the database part of the application was wrong. This installation was at a warehouse over 10x larger than any previous installaitions of the software -- And entire tables of the database (30,000+ rows typical) were being put under exclusive lock (no READS allowed!) because the original programmer was lazy. Once this was discovered, the software was debugged, replacing table locks with code locking individual rows. Once this was done, CPU usage WENT UP... which was a GOOD THING(tm)! *AND* we were able to reduce the number of CPUs to only two (and that was just for redundancy... CPU usage was still less than 1/N where N is the number of installed CPUs.
Thanks
-----Original Message----- From: Randall R Schulz [mailto:rschulz@sonic.net] Sent: Friday, January 11, 2008 2:51 PM To: opensuse@opensuse.org Subject: Re: [opensuse] Top/lsof
On Friday 11 January 2008 10:33, Kain, Becki (B.) wrote:
I read the man page of top but it's not helpful for this question. When top tells me cpu0 is being used 50.0% by sys, cpu1 is being used 65.7% by system space, how do I break down what processes are making up that 65.7%, in system space, of the cpu? And in lsof, how do you tell which cpu a process id's threads are tied to?
Why do you care?
I tends to shift rapidly, so programs like top that update once per second or so can't follow these changes, anyway.
And I don't see how "lsof" is relevant at all.
Randall Schulz
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