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:[EMAIL PROTECTED]
Sent: Friday, January 11, 2008 2:51 PM
To: [email protected]
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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