Open MPI User's Mailing List Archives

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

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• In reply to: Asad Ali: "Re: [OMPI users] open-mpi behaviour on Fedora, Ubuntu, Debian and CentOS"
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• Reply: Conboy, James: "Re: [OMPI users] open-mpi behaviour on Fedora, Ubuntu, Debian and CentOS"
• Reply: Asad Ali: "Re: [OMPI users] open-mpi behaviour on Fedora, Ubuntu, Debian and CentOS"

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

• Next message: TRINH Minh Hieu: "Re: [OMPI users] Segmentation fault when Send/Recv on heterogeneouscluster (32/64 bit machines)"
• Previous message: Sylvestre Ledru: "Re: [OMPI users] open-mpi behaviour on Fedora, Ubuntu, Debian and CentOS"
• In reply to: Asad Ali: "Re: [OMPI users] open-mpi behaviour on Fedora, Ubuntu, Debian and CentOS"
• Next in thread: Conboy, James: "Re: [OMPI users] open-mpi behaviour on Fedora, Ubuntu, Debian and CentOS"
• Reply: Conboy, James: "Re: [OMPI users] open-mpi behaviour on Fedora, Ubuntu, Debian and CentOS"
• Reply: Asad Ali: "Re: [OMPI users] open-mpi behaviour on Fedora, Ubuntu, Debian and CentOS"