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Subject: Re: [OMPI devel] Problem when using struct types at specific offsets
From: Thomas Jahns (jahns_at_[hidden])
Date: 2013-06-21 10:33:27


Hello,

On 04/08/2013 04:08 PM, Thomas Jahns wrote:
> a colleague of mine has investigated a difficult problem we traced to OpenMPI
> giving incorrectly delivered data on some struct datatypes which use specific
> offsets (on the stack in our case but the problem can be reproduced when using
> specifically chosen slices of an array). Our library is used to aggregate
> several MPI communications in a generic and transparent manner and therefore we
> need to be able to handle any combination of properly aligned offsets and
> component types.
>
> The attached example program contains the necessary steps to reproduce the problem:
>
> 1. create the struct types in question
> 2. send/recv the data
> 3. compare to reference (said comparison works on several MPICH2 versions)

our IT service provider has applied the patch to openmpi 1.6.4 and the C
test-case I provided now works but the original code which uses a bigger number
of struct dataypes still fails.

Has anyone already discovered a potential problem with the fix provided in
r28319? I'm asking because developing the C test case is quite some amount of
work and is not easily reproducible with every Fortran compiler because it
depends on the stack layout.

Regards, Thomas

-- 
Thomas Jahns
DKRZ GmbH, Department: Application software
Deutsches Klimarechenzentrum
Bundesstraße 45a
D-20146 Hamburg
Phone: +49-40-460094-151
Fax: +49-40-460094-270
Email: Thomas Jahns <jahns_at_[hidden]>