dat_lmr_sync_rdma_wDirectDAccess Transport Librardat_lmr_sync_rdma_write(3DAT)NAMEdat_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 argu‐
ment.
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 modi‐
fied contents of the memory range. It is permissible to batch synchro‐
nizations of multiple 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 incom‐
ing RDMA writes. After performing the local write, the Consumer must
call dat_lmr_sync_rdma_write() before the RDMA Write is initiated.
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-spe‐
cific 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 │Committed │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │Unsafe │
├─────────────────────────────┼─────────────────────────────┤
│Standard │uDAPL, 1.2 │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOdat_lmr_sync_rdma_read(3DAT), libdat(3LIB), attributes(5)SunOS 5.11 16 Jul 2004 dat_lmr_sync_rdma_write(3DAT)
