You probably want to use an MPI tracing tool that can break down the
times spent inside and outside of the MPI library. User vs. system
time, as you noted, can get quite blurred.
On Jul 6, 2009, at 12:48 PM, Ross Boylan wrote:
> Let total time on my slot 0 process be S+C+B+I
> = serial computations + communication + busy wait + idle
> Is there a way to find out S?
> S+C would probably also be useful, since I assume C is low.
> The problem is that I = 0, roughly, and B is big. Since B is big, the
> usual process timing methods don't work.
> If B all went to "system" as opposed to "user" time I could use the
> latter, but I don't think that's the case. Can anyone confirm that?
> If S is big, I might be able to gain by parallelizing in a different
> way. By S I mean to refer to serial computation that is part of my
> algorithm, rather than the technical fact that all the computation is
> serial on a given slot.
> I'm running R/RMPI.
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