rdmacreateeventchannel

rdma_create_event_channel is a function in the RDMA Connection Manager (RDMA CM) API used to create an event channel for receiving asynchronous RDMA CM events in user space. It returns a pointer to a structure representing the event channel, or NULL if the creation fails.

An event channel serves as the conduit through which an application receives notifications about RDMA CM state changes and connection-related events. Common events include address resolution results, route resolution results, connection requests, established connections, and disconnects. Events retrieved from the channel are obtained with rdma_get_cm_event and must be acknowledged after processing by calling rdma_ack_cm_event. The channel is typically associated with a specific RDMA communication identifier created via rdma_create_id.

Usage pattern typically involves creating the event channel, creating a RDMA ID tied to that channel, initiating address or route resolution, and then entering a loop that calls rdma_get_cm_event to handle incoming events. After handling each event, the application should acknowledge it with rdma_ack_cm_event. When the connection or application is finished, the event channel should be destroyed with rdma_destroy_event_channel to release resources.

Notes and considerations include that the event channel may be monitored using poll or select on its underlying file descriptor, enabling asynchronous event handling without busy-waiting. The lifetime of the channel is managed by the application; it should be destroyed when no longer needed. This API is distinct from completion queues used for work completions and is specifically oriented toward RDMA CM state and connection management events.

See also: rdma_create_id, rdma_resolve_addr, rdma_resolve_route, rdma_get_cm_event, rdma_ack_cm_event, rdma_destroy_event_channel.