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Subject: Re: [OMPI users] Can 2 IB HCAs give twice the bandwidth?
From: Eric Thibodeau (kyron_at_[hidden])
Date: 2008-10-19 14:21:53


Jeff Squyres wrote:
> On Oct 18, 2008, at 9:19 PM, Mostyn Lewis wrote:
>
>> Can OpenMPI do like Scali and MVAPICH2 and utilize 2 IB HCAs per machine
>> to approach double the bandwidth on simple tests such as IMB PingPong?
>
>
> Yes. OMPI will automatically (and aggressively) use as many active
> ports as you have. So you shouldn't need to list devices+ports --
> OMPI will simply use all ports that it finds in the active state. If
> your ports are on physically separate IB networks, then each IB
> network will require a different subnet ID so that OMPI can compute
> reachability properly.
>
Does this apply to all fabrics, or, at which level is this implemented
in ompi? (ie: multiple GigE nics...but I doubt it applies given the
restricted intricacies of the IP implementation)

Eric