【摘要】原文：https://www.rdmamojo.com/2013/02/22/ibv_req_notify_cq/
目录

描述
参数
返回值
例子
常见问题

描述
ibv_req_notify_cq（）在完成队列（CQ）上请求完成通知。
ibv_req_notify_cq（）当一个requested type的下一个WC(工作完成)添加到C…

原文：https://www.rdmamojo.com/2013/02/22/ibv_req_notify_cq/

返回值

例子

常见问题

描述

ibv_req_notify_cq（）在完成队列（CQ）上请求完成通知。

ibv_req_notify_cq（）当一个requested type的下一个WC(工作完成)添加到CQ时请求一个通知。调用ibv_req_notify_cq（）之前CQ中存在的任何WC(工作完成)都不会导致创建完成通知。完成通知可使用ibv_get_cq_event（）读取。

可以请求两种类型的完成事件：

请求的完成事件-当到达的[发送]或[带立即数的RDMA写入消息]带有“请求的事件”指示符集（即，远程端发布了SR(发送请求)并在send_flags中设置了IBV_SEND_SOLICITED的消息）产生的WC（成功接收or失败）添加到CQ中时产生的事件。
非请求的完成事件-在将任何WC(工作完成)添加到CQ时发生，无论它是发送还是接收工作完成，以及它是成功还是失败。

如果一个Request Completion Notification 在pending，即调用了ibv_req_notify_cq（）并且还没Completion Notification发生，则后续在相同CQ上调用ibv_req_notify_cq（）请求相同的Completion Event type将无效;

仅会生成一个完成通知。调用ibv_req_notify_cq()只有在完成通知发生后才会起作用（Callingibv_req_notify_cq()will have an effect only after the Completion Notification will occur.）。

下一个完成事件的请求完成通知（Request Completion Notification）优先于同一CQ的solicited event completion的请求完成通知（Request Completion Notification）。
如果对同一个CQ进行了多次ibv_req_notify_cq（）的调用，并且至少有一个请求将类型设置为[下一个完成](next completion)，则将[下一个完成]添加到该CQ时将生成一个完成通知（即不是为next Solicited Completion）。
Completion Notification一旦发生，如果希望获得更多的Completion Notification（完成通知），则他必须再次调用ibv_req_notify_cq（）。

原文：

ibv_req_notify_cq()requests a Completion Notification on a Completion Queue (CQ).

ibv_req_notify_cq()requests a notification when the next Work Completion of a requested type is added to the CQ. Any Work Completions that existed in the CQ before callingibv_req_notify_cq()will not result in creating a Completion Notification. The Completion Notification will be read usingibv_get_cq_event().

There are two types of Completion Events that can be requested:

Solicited Completion Event – Occurs when an incoming Send or RDMA Write with Immediate Data message with the Solicited Event indicator set (i.e. the remote side posted a Send Request with IBV_SEND_SOLICITED set in send_flags) causes a generation of a successful Receive Work Completion or any unsuccessful (either Send of Receive) Work Completion to be added to the CQ.

Unsolicited Completion Event – occurs when any Work Completion is added to the CQ, whether it is a Send or Receive Work Completion and whether is it successful or unsuccessful Work Completion.

If a Request Completion Notification is pending, i.e.ibv_req_notify_cq()was called and no Completion Notification occurred, subsequent calls toibv_req_notify_cq()with the same CQ requesting the same Completion Event type will have no effect; only one Completion Notification will be generated. Callingibv_req_notify_cq()will have an effect only after the Completion Notification will occur.

A Request Completion Notification for the next completion event takes precedence over a Request Completion Notification for a solicited event completion for the same CQ.

If multiple calls toibv_req_notify_cq()have been made for the same CQ and at least one of the requests set the type to the next completion, a Completion Notification will be generated when the next Completion is added to that CQ (i.e. not for the next Solicited Completion).

Once a Completion Notification occurred, if one wishes to get more Completions Notification, he has to callibv_req_notify_cq()again.