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

[Roland Dreier]

    Shirley> My observation is the atomic operation is not that
    Shirley> expensive.

It's just about the worst thing to do.  For example, on x86/x86-64 an
instruction with the lock; prefix is quite slow.  If you look at an
instruction level profile you can see that quite clearly.

    Shirley> I thought the path holding another AH reference to
    Shirley> prevent it to be freed?

If that were true then why would we want to reference count sends at
all?  The whole point is that a path might be destroyed before the
send is executed.

 - R.