[ofa-general] RE: tcp/rdma port unification patch in librdmacm

[Or Gerlitz]

Steve Wise wrote:
> Or maybe map PS_TCP port space to the be the unified space, and have a 
> new PS_RDMA or PS_IB port space that doesn't? At and second 
Please note that the rdma-cm derives the IB Service-ID from the port 
space and the port provided to rdma_resolve_addr - and this is done 
along the lines of the IBTA "RDMA IP CM Service" annex A11.
So we would need to have PS_IB_UD and PS_IB_RC that SID(ps=TCP, port=X) 
= SID(ps=IB_RC, port=X)
at first thought this is possible and would add too much compatibility 
issues - except for the need to provide an app with the means to sense 
if the underlying librdmacm support the _IB port spaces.

Still, I would like to avoid the case where someone runs MPI job over 
RDMA-CM over IB and librdmacm opens/bounds to all these sockets - so the 
preferred solution - for my taste would be some setting done by the user 
to have librdmacm allocate socket / carve a port - and it wouldn't be 
the default. For example, using an environment variable, e.g similar to 
the libibverbs fork support.

Or.

Or.