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Subject: Re: [OMPI users] open-mpi behaviour on Fedora, Ubuntu, Debian and CentOS
From: Ashley Pittman (ashley_at_[hidden])
Date: 2010-04-26 04:01:58


On 25 Apr 2010, at 22:27, Asad Ali wrote:

> Yes I use different machines such as
>
> machine 1 uses AMD Opterons. (Fedora)
>
> machine 2 and 3 use Intel Xeons. (CentOS)
>
> machine 4 uses slightly older Intel Xeons. (Debian)
>
> Only machine 1 gives correct results. While CentOS and Debian results are same but are wrong and different from those of machine 1.

Have you verified the are actually wrong or are they just different? It's actually perfectly possible for the same program to get different results from run to run even on the same hardware and the same OS. All floating point operations by the MPI library are expected to be deterministic but changing the process layout or and MPI settings can affect this and of course anything the application does can introduce differences as well.

Ashley.

-- 
Ashley Pittman, Bath, UK.
Padb - A parallel job inspection tool for cluster computing
http://padb.pittman.org.uk