[openib-general] [PATCH 1/2][RFC] Implement resize of CQ

[Fab Tillier]

> From: Sean Hefty [mailto:mshefty at ichips.intel.com]
> Sent: Friday, November 05, 2004 11:21 AM
> 
> Hal Rosenstock wrote:
> >>>However I'm not sure I understand why the MAD layer wants to resize
> >>>these objects -- given that the number of QPs is known in advance and
> >>>that the MAD layer can choose how many work requests to post per QP,
> >>>I'm not sure what is gained by trying to resize things dynamically.
> >>
> >>Actually, I haven't really implemented the "dynamically" part, where you
> >>resize the CQ during operation. The spec said that when you create a QP,
> >>it can be larger than what you specified. If so, I see good value in
> >>increasing the size of the associated CQ, if it is supported by the
> >>driver.
> >
> >
> > Might this be useful for redirected QPs ?
> 
> Since the client allocates the QP and CQ in this case, they would be
> responsible for resizing the CQ appropriately.  The MAD layer could
> provide queuing to prevent send queue overflow, or not, depending on how
> we want to implement it.

If the MAD layer did provide queuing to prevent overflow for the requested
(not allocated) depth, then the CQ resize is unnecessary.  I would expect
that whatever code manages the QP/CQ should provide queuing so that MAD
agents don't all have to implement queueing with respect to one another.

- Fab