I want to make sure I have the correct understanding of ibv_exp_wc.timestamp:
- is this timestamp the time when the cqe is generated?
- when is a cqe generated? For reliable transport, when the ack is received, and for unreliable transport, when all data is sent to the wire?
1.Yes, you right, the timestamp indicates (if the CQ has been creating with the IBV_EXP_WC_WITH_TIMESTAMP flag) the time the CQE has been generated.
2.Yes, you right, this time is different according to the transport mode.
Assuming you speak about Send CQE, the CQE is generated when the data is sent.