[openib-general] APM support in openib stack

[Hal Rosenstock]

On Thu, 2007-01-04 at 11:19, Tang, Changqing wrote:
> > > I understand that you considering to go on an approach 
> > which does not 
> > > involve librdmacm, so you would probably like to
> > > 
> > > 	+ use IB PORT GIDs at your initial mpi init exchange
> > > 	+ issue IB SA Path query via libibsa (which does not exist)
> > 
> > likely multipath query if you want APM
> 
> Yes, we want to have APM as well.
> 
> 
> > 
> > > 	+ establish IB RC connection (listen/connect/accept) via libibcm
> > > 
> > > Please note that such an approach is possible even with the non 
> > > existence of libibsa (similarly to what IB MPIs do today 
> > use IB PORT 
> > > LIDs [note you would need both GIDs & LIDs to have the CM working 
> > > fine]
> > 
> > There are other possibilities here too using inband (IB) exchanges.
> > libibsa is not that far away either. What is your time frame ?
> 
> Is it possible to have it in OFED 1.2 ?

I think it's possible but may require some relaxation of the 1/31
functionality freeze for this but I'm not sure yet...

-- Hal

> 
> > 
> > > at your ranks pre exchange and hardcode the other IB PATH 
> > params such 
> > > as MTU, PKEY and SL you set later into the IB RC QP.
> > > 
> > > However, a no rdma cm approach means you need to apply 
> > hacks to "guess" 
> > > the correct pkey, mtu and sl and some more limitations that 
> > eventually 
> > > you would face when coming to advanced IB deployment environments.
> > 
> > Also, you would make more work if iWARP support is of 
> > interest as well.
> > It comes "for free" or at least "for cheap" if the RDMA CM 
> > approach is taken.
> 
> We understand that, but we hope to have a connect/accept style IB
> connection setup, without IPoIB involved,
> like HP-UX IT-API(similar to uDAPL without underlying IP support), it
> works with multiple cards.
> 
> Configure 4-5 IP addresses on a single node is kind of silly.
> 
> 
> 
> --CQ
> 
> 
> > 
> > -- Hal
> > 
> > > All you have to do to use the rdma cm to require a functional IPoIB 
> > > NIC on each of the active IB PORTs, which is a trivial requirement 
> > > from the users in the Ethernet world, so why not apply it 
> > here as well ???
> > > 
> > > On the other hand moving to use the IB CM instead of 
> > emulating it via 
> > > TCP is some progress...
> > > 
> > > Or.
> > > 
> > > 
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> > 
> >