Tribblix: manual page: rsm_memseg_import

RSM_MEMSEG_IMPORT_PUTV(3RSM) Remote Shared Memory Library Functions

NAME

rsm_memseg_import_putv, rsm_memseg_import_getv - write to a segment
using a list of I/O requests

SYNOPSIS

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);

DESCRIPTION

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 the
rsm_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.

RETURN VALUES

Upon successful completion, these functions return 0. Otherwise, an
error value is returned to indicate the error.

ERRORS

The rsm_memseg_import_putv() and rsm_memseg_import_getv() functions
can return the following errors:

RSMERR_BAD_SGIO

Invalid scatter-gather structure pointer.

RSMERR_BAD_SEG_HNDL

Invalid segment handle.

RSMERR_BAD_CTLR_HNDL

Invalid controller handle.

RSMERR_BAD_OFFSET

Invalid offset.

RSMERR_BAD_LENGTH

Invalid length.

RSMERR_BAD_ADDR

Bad address.

RSMERR_INSUFFICIENT_RESOURCES

Insufficient resources.

RSMERR_INTERRUPTED

The operation was interrupted by a signal.

RSMERR_PERM_DENIED

Permission denied.

RSMERR_BARRIER_FAILURE

I/O completion error.

RSMERR_REMOTE_NODE_UNREACHABLE

Remote node not reachable.