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Subject: Re: [OMPI users] Question about '--mca btl tcp,self'
From: Ralph Castain (rhc_at_[hidden])
Date: 2014-03-14 10:11:04

On Mar 14, 2014, at 6:50 AM, Jianyu Liu <jerry_leo_at_[hidden]> wrote:

> Dear Sir/Madam,
> 1. If specified '--mca btl tcp,self', which interface application will run on, use GigE adaper OR use the OpenFabrics interface in IP over IB mode (just like a high performance GigE adapter) ?

Both - ip over ib looks just like an Ethernet adaptor

> 2. If '--mca btl tcp,self' forced application to use GigE adapter, how to force application to use OpenFabrics interface in IP over IB mode

--mca btl_tcp_if_include <ipoib-adaptor>

> 3. Does app run slower in IP over IB mode than RDMA mode?

of course - IPoIB invokes the entire TCP software stack

> Appreciating your kindly help
> Jianyu
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