[openib-general] [PATCH][1/7]ipoib performance patches -- remove ah_reap

[Roland Dreier]

    Shirley> Compared to have a single thread handling AH, I don't
    Shirley> think this atomic operation is expensive.

But freeing AHs is something that happens infrequently and can be done
asynchronously.  You're replacing that cost with two atomic operations
per send packet!

    Shirley> It is true for unicast, it has a reference count before
    Shirley> ipoib_send(). I need to look at multicast.

But can you guarantee that the AH stays around until after the send
completes (which could be an arbitrarily long delay)?

 - R.