dat_ep_post_rdma_read man page on SmartOS

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DAT_EP_POST_RDMA_READ(3DAT)			   DAT_EP_POST_RDMA_READ(3DAT)

NAME
       dat_ep_post_rdma_read - transfer all data to the local data buffer

SYNOPSIS
       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
	   )

PARAMETERS
       ep_handle
			   Handle for an instance of the Endpoint.

       num_segments
			   Number of lmr_triplets in local_iov.

       local_iov
			   I/O Vector that specifies the local buffer to fill.

       user_cookie
			   User-provided  cookie  that is returned to the Con‐
			   sumer at the completion of the RDMA	Read.  Can  be
			   NULL.

       remote_buffer
			   A  pointer  to  an  RMR  Triplet that specifies the
			   remote buffer from which the data is read.

       completion_flags
			   Flags for posted RDMA Read. The default DAT_COMPLE‐
			   TION_DEFAULT_FLAG is 0x00. Other values are as fol‐
			   lows:

			   Completion Suppression
							 DAT_COMPLETION_SUP‐
							 PRESS_FLAG

							 0x01
								 Suppress suc‐
								 cessful  Com‐
								 pletion.

			   Notification of Completion
							 DAT_COMPLE‐
							 TION_UNSIGNALLED_FLAG

							 0x04
								 Non-notifica‐
								 tion  comple‐
								 tion.	 Local
								 Endpoint must
								 be configured
								 for Notifica‐
								 tion Suppres‐
								 sion.

			   Barrier Fence
							 DAT_COMPLETION_BAR‐
							 RIER_FENCE_FLAG

							 0x08
								 Request   for
								 Barrier
								 Fence.

DESCRIPTION
       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_han‐
       dle 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 behav‐
       ior 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_COMPLE‐
       TION_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 Trans‐
       port.   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 success‐
       fully for the Endpoint  in  the	DAT_EP_STATE_DISCONNECTED  state,  the
       posted RDMA Read is immediately flushed to request_evd_handle.

RETURN VALUES
       DAT_SUCCESS
				     The operation was successful.

       DAT_INSUFFICIENT_RESOURCES
				     The operation failed due to resource lim‐
				     itations.

       DAT_INVALID_PARAMETER
				     Invalid parameter. For  example,  one  of
				     the IOV segments pointed to a memory out‐
				     side its LMR.

       DAT_INVALID_HANDLE
				     The ep_handle parameter is invalid.

       DAT_INVALID_STATE
				     A parameter is in an invalid state.  End‐
				     point  was	 not  in the DAT_EP_STATE_CON‐
				     NECTED    or    DAT_EP_STATE_DISCONNECTED
				     state.

       DAT_LENGTH_ERROR
				     The  size	of the receiving buffer is too
				     small for sending buffer data.  The  size
				     of	 the local buffer is too small for the
				     data of the remote buffer.

       DAT_PROTECTION_VIOLATION
				     Protection violation for local or	remote
				     memory  access.  Protection Zone mismatch
				     between either  an	 LMR  of  one  of  the
				     local_iov segments and the local Endpoint
				     or the rmr_context and  the  remote  End‐
				     point.

       DAT_PRIVILEGES_VIOLATION
				     Privileges	 violation for local or remote
				     memory access. Either  one	 of  the  LMRs
				     used  in local_iov is invalid or does not
				     have  the	local  write  privileges,   or
				     rmr_context does not have the remote read
				     privileges.

USAGE
       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_ALIGN‐
       MENT.

       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.

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       ┌────────────────────┬───────────────────────────┐
       │  ATTRIBUTE TYPE    │	   ATTRIBUTE VALUE	│
       ├────────────────────┼───────────────────────────┤
       │Interface Stability │ Standard: uDAPL, 1.1, 1.2 │
       ├────────────────────┼───────────────────────────┤
       │MT-Level	    │ Unsafe			│
       └────────────────────┴───────────────────────────┘

SEE ALSO
       libdat(3LIB), attributes(5)

				 Jul 16, 2004	   DAT_EP_POST_RDMA_READ(3DAT)
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