Re: [AMBER-Developers] Fortran experts, a word of advice please

From: David Case <>
Date: Tue, 24 Jul 2012 09:44:18 -0400

On Jul 24, 2012, at 8:28 AM, Jason Swails <> wrote:

> What about forcing synchronization with a bcast from commmaster's master?
> It should be fairly cheap given that the master communicator is only 2
> threads.

First, there are still lots of velocities involved. Second, each master would need to rebroadcast the data to its own subthreads.

> Another option is to define an 'extra' precision real variable to store the
> difference, which should eliminate the arbitrariness of the trailing
> decimals. You can use the 'kind' specifier, which is part of the Fortran
> 95 spec:
> real(kind=DIFF_KIND) :: small_diff = 0.0

Ouch. This whole things sounds like overagressive optimization by Intel. I'm traveling now, but I seem to remember some compiler options that enforce IEEE behavior and such. Can you try some less-agressive optimizations?


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Received on Tue Jul 24 2012 - 07:00:02 PDT
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