[openib-general] MAD queuing model

[Sean Hefty]

On Wed, 01 Sep 2004 15:30:38 -0400
Hal Rosenstock <halr at voltaire.com> wrote:

> > If a work request for a MAD cannot be immediately posted to a QP, 
> > should a call to ib_mad_post_send fail, or should the work request 
> > be queued for later?  
> 
> It could be put on a deferred send queue that would be processed when
> the next send completion occurs. This would make the access layer
> implementation a little more complicated but save the client from
> rerequesting.

I think we're in agreement that the access layer should perform the queuing, and that the queuing should be for actual work requests, which implies some of the internal layering of the code.

> > Along this same line, should a MAD requiring 
> > RMPP post multiple work requests or post a single request at a time,
> > until it completes?  (By completion, I mean the work request only, 
> > and not an RMPP response.)

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

I didn't quite follow this question.