Re: amber-developers: Testing of PIMD / NEB? (Broken in AMBER 10)

From: Scott Brozell <>
Date: Wed, 10 Sep 2008 18:06:02 -0700 (PDT)


On Tue, 9 Sep 2008, Wei Zhang wrote:

> I think I found the bug which causes full PIMD fail at 8 cpus. In
> force.f and runmd.f
> there are the codes like the following:
> mpi_reduce( ..., commmaster, ... )
> which should be replaced by:
> if(master) mpi_reduce( ..., commmaster, ... )
> once we fix these, the problem will be gone.

I haven't examined this code, but:
mpi_reduce is a collective operation and is called by all processes
in a group. If you are correct then the source of this bug is probably
the confusing naming of masters. It seems that the name master should have
been retired with the multisander approach.

History will repeat itself. At the very least some clear comments with
examples seem appropriate in multisander.f for using the various com's.
Naturally, I would rename master with perhaps master_of_sander_group.

Received on Thu Sep 11 2008 - 08:43:05 PDT
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