[openib-general] [RFC] [PATCH 2/7] ib_multicast 2.6.20: add ib_multicast module to track join requests from the same port

[Michael S. Tsirkin]

Quoting r. Sean Hefty <sean.hefty at intel.com>:
> >Multiple distinct mcmember_rec queries could get us the same mcast group.
> >Say MTU > 256 and MTU > 512 look different but actually will get
> >same group in practice.
> >
> >Say 2 clients ask for these 2 queries.
> >What will be in the ib_sa_mcmember_rec in this case?
> 
> The module currently does not handle queries in as complex a way as the SA.
> The current matching is limited to equality comparisons against the local
> mcmember record.  (See cmp_rec() in multicast.c.)  If there's a need to expand
> the comparisons, that can be done.

Yes, I think supporting more queries is required in real world.
For heterogenious clusters, it seems we already need something like
IB_SA_LTE at least for the rate selector.

It is somewhat unfortunate that we are duplicating the SA logic
at the endnode in kernel memory here - current sa module has
the advantage in that it just packs all data into a mad and sends it out.
Something to think about.

-- 
MST