dat_lmr_sync_rdma_write(3DAT)			     Direct Access Transport Library Functions			     dat_lmr_sync_rdma_write(3DAT)

NAME

       dat_lmr_sync_rdma_write - synchronize local memory with RDMA write on non-coherent memory

SYNOPSIS

       cc [ flag... ] file... -ldat [ library... ]
       #include <dat/udat.h>

       DAT_RETURN
	   dat_lmr_sync_rdma_write (
	   IN DAT_IA_HANDLE ia_handle,
	   IN const DAT_LMR_TRIPLET *local_segments,
	   IN DAT_VLEN num_segments
	   )

PARAMETERS

       ia_handle	 A handle for an open instance of the IA.

       local_segments	 An array of buffer segments.

       num_segments	 The number of segments in the local_segments argument.

DESCRIPTION

       The dat_lmr_sync_rdma_write() function makes effects of an incoming RDMA Write operation visible to the Consumer. This operation guarantees
       consistency by locally invalidating the non-coherent cache whose buffer has been populated by remote peer RDMA write operations.

       The dat_lmr_sync_rdma_write() function is needed if and only if the Provider attribute specifies that this operation  is  needed  after	an
       incoming RDMA Write operation. The Consumer must call dat_lmr_sync_rdma_write() before reading data from a memory range in this region that
       was the target of an incoming RDMA Write operation. The dat_lmr_sync_rdma_write() function must be called after the  RDMA  Write  operation
       completes, and the memory range that was modified by the RDMA Write must be supplied by the caller in the local_ segments array. After this
       call returns, the Consumer may safely see the modified contents of the memory range. It is permissible to batch synchronizations of  multi-
       ple  RDMA  Write operations in a single call by passing a local_segments array that includes all modified memory ranges. The local_segments
       entries need not contain the same LMR and need not be in the same Protection Zone.

       The Consumer must also use dat_lmr_sync_rdma_write() when performing local writes to a memory range that was  or  will  be  the	target	of
       incoming  RDMA  writes.	After performing the local write, the Consumer must call dat_lmr_sync_rdma_write() before the RDMA Write is initi-
       ated.  Conversely, after an RDMA Write completes, the Consumer must call dat_lmr_sync_rdma_write() before performing a local write  to  the
       same range.

       If  the	Provider attribute specifies that this operation is needed and the Consumer attempts to read from a memory range in an LMR without
       properly synchronizing using dat_lmr_sync_rdma_write(), the returned contents are undefined. If the Consumer attempts to write to a  memory
       range without properly synchronizing, the contents of the memory range become undefined.

RETURN VALUES

       DAT_SUCCESS		The operation was successful.

       DAT_INVALID_HANDLE	The DAT handle is invalid.

       DAT_INVALID_PARAMETER	One  of  the parameters is invalid. For example, the address range for a local segment fell outside the boundaries
				of the corresponding Local Memory Region or the LMR handle was invalid.

USAGE

       Determining when an RDMA Write completes and determining which memory range was modified is the Consumer's responsibility. One  possibility
       is  for	the  RDMA  Write initiator to post a Send DTO message after each RDMA Write that identifies the range in the body of the Send. The
       Consumer at the target of the RDMA Write can receive the message and know when and how to call dat_lmr_sync_rdma_write().

       This call ensures that the Provider receives a coherent view of the buffer contents after a subsequent remote RDMA Write  operation.  After
       the  call  completes, the Consumer can be assured that all platform-specific buffer and cache updates have been performed, and that the LMR
       range has consistency with the Provider hardware. Any subsequent read by the Consumer can  void	this  consistency.  The  Provider  is  not
       required to detect such access.

       The action performed on the cache before the RDMA Write depends on the cache type:

	   o	  I/O noncoherent cache will be flushed.

	   o	  CPU noncoherent cache will be invalidated.

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard: uDAPL, 1.2	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Unsafe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       dat_lmr_sync_rdma_read(3DAT), libdat(3LIB), attributes(5)

SunOS 5.11							    16 Jul 2004 				     dat_lmr_sync_rdma_write(3DAT)