[openib-general] QP sq->tail always = 0

[Sean Hefty]

Roland Dreier wrote:
> Are you seeing any send completions on the CQ attached to the send
> queue?  One possibility is that you're not generating any send
> completions because you created your CQ with a sq_sig_type of
> IB_SIGNAL_REQ_WR and then posting send requests without the
> IB_SEND_SIGNALED flag.
> 
> (The IB_SIGNAL_REQ_WR flag means that not all send requests posted to
> the send queue will generate a completion -- only those marked with
> the IB_SEND_SIGNALED flag.  However, the driver can't free a send
> request from the send queue until it knows it has completed, and the
> only way for the driver to know that is to see a completion for the
> given request or a later request.  Requests on a queue always complete
> in order, so if a later request completes and generates a completion,
> the driver can also free any earlier unsignaled requests)

If the code is based on cmpost, this is likely the case.  Cmpost creates the 
QP with IB_SIGNAL_REQ_WR, but does not set the IB_SEND_SIGNALED flag.

Since people are refering to this as a sample, I will look at changing the 
code to avoid confusing people.

- Sean