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Subject: Re: [OMPI users] MXM vs OpenIB
From: Brock Palen (brockp_at_[hidden])
Date: 2013-01-22 20:33:09


>> You sound like our vendors, "what is your app"
>
> ;-) I used to be one.
>
> Ideally OMPI should do the switch between MXM/RC/XRC internally in the transport layer. Unfortunately,
> we don't have such smart selection logic. Hopefully IB vendors will fix some day.

I actually looked in the openib-hca.ini (working from memory) to try and find what the default queues were, and I actually couldn't figure it out. The ConnectX entry doesn't have a default, and the 'default default' also doesn't have an entry.

I need to dig into ompi_info, got distracted by an intel compiler bug, ADD for admin/user support folks.

>
>>
>> Note most of our users run just fine with the standard Peer-Peer queues, default out the box OpenMPI.
>
> The P2P queue is fine, but most like using XRC your users will observe better performance. This is not just scalability.

Cool thanks for all the input, I wonder why peer-to-peer is the default, I know XRC requires hardware support,

>
> - Pasha
>
>
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