Re: wall clock vs secs/step metrics

From: Peter Freddolino (petefred_at_ks.uiuc.edu)
Date: Tue Sep 05 2006 - 12:15:36 CDT

To more directly answer your question, the benchmark time is going to be
more properly representative for what you'll get in a production run.

On Tue, Sep 05, 2006 at 10:02:29AM -0700, Brian Bennion wrote:
>
> Hello,
>
> I have been comparing timing differences between NAMD 2.5 and 2.6 on the
> apoa1 benchmark.
> I noticed something strange. The secs/step for 32 cpus decrease
> 0.077 to 0.070 which I thought was great, however, the final wall clock
> actually increase from 51.43s (namd2.5) to 55.11s (namd2.6) for the same
> 32 cpus.
>
> Then I looked at the last timing output statement at step 500 and saw that
> namd2.5 was 45.03s while namd2.6 was 41.72s. So the ouputs during runtime
> seem to be congruent, but the final wall clocks don't follow in the same
> direction.
>
>
> My questions are then, which metric should be trusted and secondly why are
> the final wall clock values backwards?
>
> Thank you for your help.
>
> brian
>
> ************************************************
> Brian Bennion, Ph.D.
> Biosciences Directorate
> Lawrence Livermore National Laboratory
> P.O. Box 808, L-446 bennion1_at_llnl.gov
> 7000 East Avenue phone: (925) 422-5722
> Livermore, CA 94550 fax: (925) 424-5513
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