|DAT_EP_POST_RDMA_READ(3DAT)||Direct Access Transport Library Functions||DAT_EP_POST_RDMA_READ(3DAT)|
cc [ flag... ] file... -ldat [ library... ] #include <dat/udat.h> DAT_RETURN dat_ep_post_rdma_read ( IN DAT_EP_HANDLE ep_handle, IN DAT_COUNT num_segments, IN DAT_LMR_TRIPLET *local_iov, IN DAT_DTO_COOKIE user_cookie, IN DAT_RMR_TRIPLET *remote_buffer, IN DAT_COMPLETION_FLAGS completion_flags )
Notification of Completion
The dat_ep_post_rdma_read() function requests the transfer of all the data specified by the remote_buffer over the connection of the ep_handle Endpoint into the local_iov.
The num_segments parameter specifies the number of segments in the local_iov. The local_iov segments are filled in the I/O Vector order until the whole message is received. This ensures that all the "front" segments of the local_iov I/O Vector are completely filled, only one segment is partially filled, if needed, and all segments that follow it are not filled at all.
The user_cookie allows Consumers to have unique identifiers for each DTO. These identifiers are completely under user control and are opaque to the Provider. There is no requirement on the Consumer that the value user_cookie should be unique for each DTO. The user_cookie is returned to the Consumer in the Completion event for the posted RDMA Read.
A Consumer must not modify the local_iov or its content until the DTO is completed. When a Consumer does not adhere to this rule, the behavior of the Provider and the underlying Transport is not defined. Providers that allow Consumers to get ownership of the local_iov but not the memory it specifies back after the dat_ep_post_rdma_read() returns should document this behavior and also specify its support in Provider attributes. This behavior allows Consumers full control of the local_iov after dat_ep_post_rdma_read() returns. Because this behavior is not guaranteed by all Providers, portable Consumers should not rely on this behavior. Consumers should not rely on the Provider copying local_iov information.
The completion of the posted RDMA Read is reported to the Consumer asynchronously through a DTO Completion event based on the specified completion_flags value. The value of DAT_COMPLETION_UNSIGNALLED_FLAG is only valid if the Endpoint Request Completion Flags DAT_COMPLETION_UNSIGNALLED_FLAG. Otherwise, DAT_INVALID_PARAMETER is returned.
The DAT_SUCCESS return of the dat_ep_post_rdma_read() is at least the equivalent of posting an RDMA Read operation directly by native Transport. Providers should avoid resource allocation as part of dat_ep_post_rdma_read() to ensure that this operation is nonblocking and thread safe for an UpCall.
The operation is valid for the Endpoint in the DAT_EP_STATE_CONNECTED and DAT_EP_STATE_DISCONNECTED states. If the operation returns successfully for the Endpoint in the DAT_EP_STATE_DISCONNECTED state, the posted RDMA Read is immediately flushed to request_evd_handle.
For best RDMA Read operation performance, the Consumer should align each buffer segment of local_iov to the Optimal Buffer Alignment attribute of the Provider. For portable applications, the Consumer should align each buffer segment of local_iov to the DAT_OPTIMAL_ALIGNMENT.
If connection was established without outstanding RDMA Read attributes matching on Endpoints on both sides (outstanding RDMA Read outgoing on one end is larger than the outstanding RDMA Read incoming on the other end), connection is broken when the number of incoming RDMA Read exceeds the outstanding RDMA Read incoming attribute of the Endpoint. The Consumer can use its own flow control to ensure that it does not post more RDMA Reads then the remote EP outstanding RDMA Read incoming attribute is. Thus, they do not rely on the underlying Transport enforcing it.
See attributes(7) for descriptions of the following attributes:
|ATTRIBUTE TYPE||ATTRIBUTE VALUE|
|Interface Stability||Standard: uDAPL, 1.1, 1.2|
|July 16, 2004||OmniOS|