[Cialug] user vs. sys cpu time

[Jesse Welling]

To help diagnose what's going on it would probably be best to post the
threaded code... or if you don't want to reveal the inner workings
just a more detailed out line of how it is structured...

On 6/21/07, Jerry Heiselman <jweida at gmail.com> wrote:
> On 6/21/07, Kendall Bailey <krbailey at gmail.com> wrote:
>
> > I have a math optimization app that runs for several minutes on a dual
> > proc/dual core opteron SLES 9 box.  Plenty of RAM.  It uses 4 threads
> > to do some parallel computation to take advantage of all 4 cpu cores.
> > Looking at 'top', or using 'time' to measure cpu time, it's logging
> > 30% or more sys time vs. 60-70% user time during the parallel phases.
> > I ran it with 'strace -c' and that says only 0.003 seconds are spent
> > in system calls.  No system calls going on at all on the 4 threads.
> > So what does the 'sys' time represent as reported by top?
> >
> > Thanks.
> > Kendall
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>
> I'm not very knowledgable in this area, but perhaps some of the libraries
> you are using have to make syscall's to complete.  Perhaps something to do
> with the threading.
>
> Like I said, it's just a guess.
>
> --
> Jerry H
> jweida [-at-] gmail [-dot-] com
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