After a message transfer completes, either with or without error, the WQE is retired from the respective queue (SQ or RQ) and a completion notice is recorded in the CQ associated with the respective queue (SQ or RQ). The entry created in the CQ is referred to as a Completion Queue Entry, or CQE (pronounced “cookie”). Each CQE contains the 64-bit WR ID that was assigned to the original message transfer WR posted to the SQ or the RQ by software. This permits software to associate a CQE with a previously issued message transfer WR.
The verbs that are associated with CQs are:
Set Completion Event Handler.
Poll For Completion.
Request Completion ...