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Subject: Re: [OMPI users] Infiniband performance Problem and stalling
From: Paul Kapinos (kapinos_at_[hidden])
Date: 2012-08-28 04:13:21


Randolph,
after reading this:

On 08/28/12 04:26, Randolph Pullen wrote:
> - On occasions it seems to stall indefinately, waiting on a single receive.

... I would make a blind guess: are you aware about IB card parameters for
registered memory?
http://www.open-mpi.org/faq/?category=openfabrics#ib-low-reg-mem

"Waiting forever" for a single operation is one of symptoms of the problem
especially in 1.5.3.

best,
Paul

P.S. the lower performance with 'big' chinks is known phenomenon, cf.
http://www.scl.ameslab.gov/netpipe/
(image on bottom of the page). But the chunk size of 64k is fairly small

-- 
Dipl.-Inform. Paul Kapinos   -   High Performance Computing,
RWTH Aachen University, Center for Computing and Communication
Seffenter Weg 23,  D 52074  Aachen (Germany)
Tel: +49 241/80-24915