[mvapich-discuss] Re: loopback with mvapich2-1.2p1

[gossips J]

This env variable does not turn out into Loopback connections. I ran with
the adapter which supports loopback connection as well.
It makes non-loopback connections only.


On Tue, Aug 4, 2009 at 7:24 PM, Dhabaleswar Panda
<panda at cse.ohio-state.edu>wrote:

> > Re factored the question,
> > Whether mvapich2-1.2p1 supports loopback connections??
>
> Yes.
>
> > As with Intel MPI we can specify device as "rdma" or "rdssm" where
> "rdssm"
> > does _no_ loopback whereas "rdma" does both loopback as well as
> non-loopback
> > connections with both IMB-MPI1 and IMB-EXT.
>
> The runtime environmental parameter MV2_USE_SHARED_MEM controls this.  By
> default, this is set to 1 which uses intra-node shared memory for
> communication. If this parameter is set to 0, communication takes place
> over loopback connection.
>
> More details on this parameter are available from MVAPICH2 1.2p1 user
> guide at the following URL:
>
>
> http://mvapich.cse.ohio-state.edu/support/user_guide_mvapich2-1.4rc1.html#x1-15600011.70
>
> However, before changing this parameter to 0, you need to make sure that
> the underlying network adapter supports loopback connection. Some adapters
> do not support such functionality and this option (MV2_USE_SHARED_MEM=0)
> may not work with these adapters.
>
> Hope this helps.
>
> DK
>
> >
> > On Tue, Aug 4, 2009 at 11:59 AM, gossips J <polk678 at gmail.com> wrote:
> >
> > > Hi,
> > > I would like to know whether mvapcih2-1.2p1 makes loopback connections
> or
> > > not.
> > >
> > > Does anybody have idea on the same?
> > >
> > > I could not locate this details on FAQ as well as user guide for the
> same.
> > >
> > > Thanks,
> > > Polk.
> > >
> >
>
>
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