[openib-general] IB Address Translation service

[Roland Dreier]

    Roland> First, let's understand the problem we're trying to solve.
    Roland> Who are the consumers of this address translation service?

    shaharf> Any ULPs at user & kernel, and also some
    shaharf> applications.

I think this is too general an answer.  We should be designing based
on specific ULPs and applications.  For example, I don't see anything
particularly useful to IPoIB in this API.  Perhaps Libor can comment
on how this API works for SDP.

What application would use functions like ib_at_ips_by_gid90 or
ib_at_ips_by_subnet()?

    shaharf> My take right now is to implement a kernel based
    shaharf> mechanism and a user mode library to interface it.  There
    shaharf> are other feasible solutions. I would really like you
    shaharf> have your suggestions and preferences.

Unless there is a real kernel consumer that needs something this
elaborate, I would prefer to implement this sort of caching service as
a userspace daemon/library.  This allows for more sophisticated
implementations (eg persistent caches) and also makes debugging and
maintenance easier.

    shaharf> I think that starting with the APIs is a valid approach
    shaharf> that has its own advantages and disadvantages.
 
Sure, it's always good to have code in hand to start a discussion.
But in this case the API seems to be far ahead of its consumers, so it
ends up feeling overengineered to me.

 - R.