[openib-general] IPoIB CM

[Michael S. Tsirkin]

> Quoting r. Or Gerlitz <ogerlitz at voltaire.com>:
> Subject: Re: [openib-general] IPoIB CM
> 
> Sean Hefty wrote:
> > Would you expect that the use of this code would likely result in creating 
> > all-to-all connections between all nodes?  In particular, I'm thinking about MPI 
> > applications that use all-to-all connections.  I realize this is done at the 
> > RDMA layer, but is there anything that would end up connecting all of the nodes 
> > via iopib?
> 
> yes,
> 
> If the MPI uses TCP/UDP over the IPoIB subnet for its (i,j) 
> communication for all ranks 1 < i < j < n then yes, an all-to-all 
> connection establishment model or an actual call to mpi-all-to-all would 
> result in IPoIB CM connecting all-to-all . If the MPI uses IB (eg 
> through uDAPL or libibverbs/librdmacm they would connect all-to-all 
> through the cma.

And if MPI is run on top of IPoIB UD mode, it won't create connections
but each node might have address handles for each of the other nodes.

-- 
MST