[openib-general] MAD queuing model

[Roland Dreier]

    Sean> I asked this more based on what the response to the first
    Sean> question was, along with how the layering worked.  It also
    Sean> comes down to some fairness, since while a large RMPP
    Sean> request is being sent, responses for other MADs may be
    Sean> queued behind it, which could result in timeouts on other
    Sean> MADs.  Ideally, correct RMPP windowing would avoid this type
    Sean> of condition.

I'd be inclined not to worry about this type of fairness for our
initial implementation.  If it turns out that RMPP sends with 10
megabyte windows are starving other sends, then we can add more
sophisticated queue processing (since our MAD send queue handling will
be nicely encapsulated in the core MAD layer ;).

For example one could have a scheduler that limits the number of
consecutive sends with the same TID if other sends are waiting --
however as I said I don't think this should be in our first version.

 - R.