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Subject: [OMPI users] Program deadlocks, on simple send/recv loop
From: Brock Palen (brockp_at_[hidden])
Date: 2009-12-01 10:46:54


The attached code, is an example where openmpi/1.3.2 will lock up, if
ran on 48 cores, of IB (4 cores per node),
The code loops over recv from all processors on rank 0 and sends from
all other ranks, as far as I know this should work, and I can't see
why not.
Note yes I know we can do the same thing with a gather, this is a
simple case to demonstrate the issue.
Note that if I increase the openib eager limit, the program runs,
which normally means improper MPI, but I can't on my own figure out
the problem with this code.

Any input on why code like this locks up, unless we up the eager
buffer would be helpful, as we should be be having to up the buffer
size, just to make code run, makes me feel hacky and dirty.


Brock Palen
www.umich.edu/~brockp
Center for Advanced Computing
brockp_at_[hidden]
(734)936-1985