ibv_req_notify_cq() requests a completion notification on the completion queue (CQ)
cq.
Upon the addition of a new CQ entry (CQE) to
cq, a completion event will be added to the completion channel associated
with the CQ.
If the argument
solicited_only is zero, a completion event is generated for any new CQE. If
solicited_only is non-zero, an event is only generated for a new CQE with that is
considered "solicited." A CQE is solicited if it is a receive
completion for a message with the Solicited Event header bit set, or
if the status is not successful. All other successful receive
completions, or any successful send completion is unsolicited.