- write to a segment using a list of I/O requests
cc [ flag... ] file... –lrsm [ library... ] #include <rsmapi.h> int rsm_memseg_import_putv(rsm_scat_gath_t *sg_io);
int rsm_memseg_import_getv(rsm_scat_gath_t *sg_io);
The rsm_memseg_import_putv() and rsm_memseg_import_getv() functions provide for using a list of I/O requests rather than a single source and destination address as is done for thersm_memseg_import_put(3RSM) and rsm_memseg_import_get(3RSM) functions.
The I/O vector component of the scatter-gather list (sg_io), allows specifying local virtual addresses or local_memory_handles. When a local address range is used repeatedly, it is efficient to use a handle because allocated system resources (that is, locked down local memory) are maintained until the handle is freed. The supporting functions for handles are rsm_create_localmemory_handle(3RSM) and rsm_free_localmemory_handle(3RSM).
Virtual addresses or handles may be gathered into the vector for writing to a single remote segment, or a read from a single remote segment may be scattered to the vector of virtual addresses or handles.
Implicit mapping is supported for the scatter-gather type of access. The attributes of the extension library for the specific interconnect are used to determine whether mapping is necessary before any scatter-gather access. If mapping of the imported segment is a prerequisite for scatter-gather access and the mapping has not already been performed, an implicit mapping is performed for the imported segment. The I/O for the vector is then initiated.
I/O for the entire vector is initiated before returning. The barrier mode attribute of the import segment determines if the I/O has completed before the function returns. A barrier mode attribute setting of IMPLICIT guarantees that the transfer of data is completed in the order as entered in the I/O vector. An implicit barrier open and close surrounds each list entry. If an error is detected, I/O for the vector is terminated and the function returns immediately. The residual count indicates the number of entries for which the I/O either did not complete or was not initiated.
The number of entries in the I/O vector component of the scatter-gather list is specified in the io_request_count field of the rsm_scat_gath_t pointed to by sg_io. The io_request_count is valid if greater than 0 and less than or equal to RSM_MAX_SGIOREQS. If io_request_count is not in the valid range, rsm_memseg_import_putv() and rsm_memseg_import_getv() returns RSMERR_BAD_SGIO.
Optionally, the scatter-gather list allows support for an implicit signal post after the I/O for the entire vector has completed. This alleviates the need to do an explicit signal post after ever I/O transfer operation. The means of enabling the implicit signal post involves setting the flags field within the scatter-gather list to RSM_IMPLICIT_SIGPOST. The flags field may also be set to RSM_SIG_POST_NO_ACCUMULATE, which will be passed on to the signal post operation when RSM_IMPLICIT_SIGPOST is set.
Upon successful completion, these functions return 0. Otherwise, an error value is returned to indicate the error.
The rsm_memseg_import_putv() and rsm_memseg_import_getv() functions can return the following errors:
Invalid scatter-gather structure pointer.
Invalid segment handle.
Invalid controller handle.
The operation was interrupted by a signal.
I/O completion error.
Remote node not reachable.
See attributes(5) for descriptions of the following attributes: