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Subject: Re: [OMPI users] Regarding the execution time calculation
From: Jingcha Joba (pukkimonkey_at_[hidden])
Date: 2012-05-07 20:31:00


Jeff,
So in the above stated example, end-start will be: <whatever the solver
took> + 20ms ?

(time slice of P2 + P3 = 20ms)

On Mon, May 7, 2012 at 1:42 PM, Jeff Squyres (jsquyres)
<jsquyres_at_[hidden]>wrote:

> On May 7, 2012, at 2:39 PM, Jingcha Joba wrote:
>
> > OK.This explains that if a process gets "migrated" from one CPU to
> another, the time is not "affected". But it still doesn't explain if the
> process gets scheduled back to the same CPU.
>
> MPI_Wtime() doesn't tell you any of this stuff. It just tells you the
> time *right now*. Basically, MPI_Wtime() can be used to compute wall-clock
> timings (which are really the only relevant timings when measuring
> delivered performance, anyway).
>
> What happens before or after that is not covered in the scope of
> MPI_Wtime().
>
> --
> Jeff Squyres
> jsquyres_at_[hidden]
> For corporate legal information go to:
> http://www.cisco.com/web/about/doing_business/legal/cri/
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>
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