dat_srq_create(3DATDirect Access Transport Library Functiodat_srq_create(3DAT)NAMEdat_srq_create - create an instance of a shared receive queue
SYNOPSIS
cc [ flag... ] file... -ldat [ library... ]
#include <dat/udat.h>
DAT_RETURN
dat_srq_create (
IN DAT_IA_HANDLE ia_handle,
IN DAT_PZ_HANDLE pz_handle,
IN DAT_SRQ_ATTR *srq_attr,
OUT DAT_SRQ_HANDLE *srq_handle
)
PARAMETERS
ia_handle A handle for an open instance of the IA to which the
created SRQ belongs.
pz_handle A handle for an instance of the Protection Zone.
srq_attr A pointer to a structure that contains Consumer-
requested SRQ attributes.
srq_handle A handle for the created instance of a Shared Receive
Queue.
DESCRIPTION
The dat_srq_create() function creates an instance of a Shared Receive
Queue (SRQ) that is provided to the Consumer as srq_handle. If the
value of DAT_RETURN is not DAT_SUCCESS, the value of srq_handle is not
defined.
The created SRQ is unattached to any Endpoints.
The Protection Zone pz_handle allows Consumers to control what local
memory can be used for the Recv DTO buffers posted to the SRQ. Only
memory referred to by LMRs of the posted Recv buffers that match the
SRQ Protection Zone can be accessed by the SRQ.
The srq_attributes argument specifies the initial attributes of the
created SRQ. If the operation is successful, the created SRQ will have
the queue size at least max_recv_dtos and the number of entries on the
posted Recv scatter list of at lease max_recv_iov. The created SRQ can
have the queue size and support number of entries on post Recv buffers
larger than requested. Consumer can query SRQ to find out the actual
supported queue size and maximum Recv IOV.
The Consumer must set low_watermark to DAT_SRQ_LW_DEFAULT to ensure
that an asynchronous event will not be generated immediately, since
there are no buffers in the created SRQ. The Consumer should set the
Maximum Receive DTO attribute and the Maximum number of elements in IOV
for posted buffers as needed.
When an associated EP tries to get a buffer from SRQ and there are no
buffers available, the behavior of the EP is the same as when there are
no buffers on the EP Recv Work Queue.
RETURN VALUES
DAT_SUCCESS
The operation was successful.
DAT_INSUFFICIENT_RESOURCES
The operation failed due to resource limitations.
DAT_INVALID_HANDLE
Either ia_handle or pz_handle is an invalid DAT handle.
DAT_INVALID_PARAMETER
One of the parameters is invalid. Either one of the requested SRQ
attributes was invalid or a combination of attributes is invalid.
DAT_MODEL_NOT_SUPPORTED
The requested Model was not supported by the Provider.
USAGE
SRQ is created by the Consumer prior to creation of the EPs that will
be using it. Some Providers might restrict whether multiple EPs that
share a SRQ can have different Protection Zones. Check the
srq_ep_pz_difference_support Provider attribute. The EPs that use SRQ
might or might not use the same recv_evd.
Since a Recv buffer of SRQ can be used by any EP that is using SRQ, the
Consumer should ensure that the posted Recv buffers are large enough to
receive an incoming message on any of the EPs.
If Consumers do not want to receive an asynchronous event when the num‐
ber of buffers in SRQ falls below the Low Watermark, they should leave
its value as DAT_SRQ_LW_DEFAULT. If Consumers do want to receive a
notification, they can set the value to the desired one by calling
dat_srq_set_lw(3DAT).
SRQ allows the Consumer to use fewer Recv buffers then posting the max‐
imum number of buffers for each connection. If the Consumer can upper
bound the number of incoming messages over all connections whose local
EP is using SRQ, then instead of posting this maximum for each connec‐
tion the Consumer can post them for all connections on SRQ. For exam‐
ple, the maximum utilized link bandwidth divided over the message size
can be used for an upper bound.
Depending on the underlying Transport, one or more messages can arrive
simultaneously on an EP that is using SRQ. Thus, the same EP can have
multiple Recv buffers in its possession without these buffers being on
SRQ or recv_evd.
Since Recv buffers can be used by multiple connections of the local EPs
that are using SRQ, the completion order of the Recv buffers is no
longer guaranteed even when they use of the same recv_evd. For each
connection the Recv buffers completion order is guaranteed to be in the
order of the posted matching Sends to the other end of the connection.
There is no ordering guarantee that Receive buffers will be returned in
the order they were posted even if there is only a single connection
(Endpoint) associated with the SRQ. There is no ordering guarantee
between different connections or between different recv_evds.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard: uDAPL, 1.2 │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOdat_srq_free(3DAT), dat_srq_post_recv(3DAT), dat_srq_query(3DAT),
dat_srq_resize(3DAT), dat_srq_set_lw(3DAT), libdat(3LIB), attributes(5)SunOS 5.10 11 Sep 2006 dat_srq_create(3DAT)
