DAT_SRQ_RESIZE(3DAT) Direct Access Transport Library Functions


NAME


dat_srq_resize - modify the size of the shared receive queue

SYNOPSIS


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

DAT_RETURN
dat_srq_resize (
IN DAT_SRQ_HANDLE srq_handle,
IN DAT_COUNT srq_max_recv_dto
)


PARAMETERS


srq_handle
A handle for an instance of the SRQ.


srq_max_recv_dto
The new maximum number of Recv DTOs that Shared
Receive Queue must hold.


DESCRIPTION


The dat_srq_resize() function modifies the size of the queue of SRQ.


Resizing of Shared Receive Queue should not cause any incoming messages
on any of the EPs that use the SRQ to be lost. If the number of
outstanding Recv buffers on the SRQ is larger then the requested
srq_max_recv_dto, the operation returns DAT_INVALID_STATE and do not
change SRQ. This includes not just the buffers on the SRQ but all
outstanding Receive buffers that had been posted to the SRQ and whose
completions have not reaped yet. Thus, the outstanding buffers include
the buffers on SRQ, the buffers posted to SRQ at are at SRQ associated
EPs, and the buffers posted to SRQ for which completions have been
generated but not yet reaped by Consumer from recv_evds of the EPs that
use the SRQ.


If the requested srq_max_recv_dto is below the SRQ low watermark, the
operation returns DAT_INVALID_STATE and does not change SRQ.

RETURN VALUES


DAT_SUCCESS
The operation was successful.


DAT_INVALID_HANDLE
The srq_handle argument is an invalid DAT
handle.


DAT_INVALID_PARAMETER
The srq_max_recv_dto argument is invalid.


DAT_INSUFFICIENT_RESOURCES
The operation failed due to resource
limitations.


DAT_INVALID_STATE
Invalid state. Either the number of entries
on the SRQ exceeds the requested SRQ queue
length or the requested SRQ queue length is
smaller than the SRQ low watermark.


USAGE


The dat_srq_resize() function is required not to lose any buffers. Thus,
it cannot shrink below the outstanding number of Recv buffers on SRQ.
There is no requirement to shrink the SRQ to return DAT_SUCCESS.


The quality of the implementation determines how closely to the Consumer-
requested value the Provider shrinks the SRQ. For example, the Provider
can shrink the SRQ to the Consumer-requested value and if the requested
value is smaller than the outstanding buffers on SRQ, return
DAT_INVALID_STATE; or the Provider can shrink to some value larger than
that requested by the Consumer but below current SRQ size; or the
Provider does not change the SRQ size and still returns DAT_SUCCESS.

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_srq_create(3DAT), dat_srq_free(3DAT), dat_srq_post_recv(3DAT),
dat_srq_query(3DAT), dat_srq_set_lw(3DAT), libdat(3LIB), attributes(5)


July 16, 2004 DAT_SRQ_RESIZE(3DAT)