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NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | RETURN VALUE | NOTES | CONNECTION PROPERTIES | INFINIBAND SPECIFIC | IWARP SPECIFIC | SEE ALSO | COLOPHON |
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RDMA_CONNECT(3) Librdmacm Programmer's Manual RDMA_CONNECT(3)
rdma_connect - Initiate an active connection request.
#include <rdma/rdma_cma.h>
int rdma_connect (struct rdma_cm_id *id, struct rdma_conn_param
*conn_param);
id RDMA identifier.
conn_param connection parameters. See CONNECTION PROPERTIES
below for details.
For an rdma_cm_id of type RDMA_PS_TCP, this call initiates a
connection request to a remote destination. For an rdma_cm_id of
type RDMA_PS_UDP, it initiates a lookup of the remote QP
providing the datagram service.
Returns 0 on success, or -1 on error. If an error occurs, errno
will be set to indicate the failure reason.
Users must have resolved a route to the destination address by
having called rdma_resolve_route or rdma_create_ep before calling
this routine.
The following properties are used to configure the communication
and specified by the conn_param parameter when connecting or
establishing datagram communication.
private_data
References a user-controlled data buffer. The contents of
the buffer are copied and transparently passed to the
remote side as part of the communication request. May be
NULL if private_data is not required.
private_data_len
Specifies the size of the user-controlled data buffer.
Note that the actual amount of data transferred to the
remote side is transport dependent and may be larger than
that requested.
responder_resources
The maximum number of outstanding RDMA read and atomic
operations that the local side will accept from the remote
side. Applies only to RDMA_PS_TCP. This value must be
less than or equal to the local RDMA device attribute
max_qp_rd_atom and remote RDMA device attribute
max_qp_init_rd_atom. The remote endpoint can adjust this
value when accepting the connection.
initiator_depth
The maximum number of outstanding RDMA read and atomic
operations that the local side will have to the remote
side. Applies only to RDMA_PS_TCP. This value must be
less than or equal to the local RDMA device attribute
max_qp_init_rd_atom and remote RDMA device attribute
max_qp_rd_atom. The remote endpoint can adjust this value
when accepting the connection.
flow_control
Specifies if hardware flow control is available. This
value is exchanged with the remote peer and is not used to
configure the QP. Applies only to RDMA_PS_TCP.
retry_count
The maximum number of times that a data transfer operation
should be retried on the connection when an error occurs.
This setting controls the number of times to retry send,
RDMA, and atomic operations when timeouts occur. Applies
only to RDMA_PS_TCP.
rnr_retry_count
The maximum number of times that a send operation from the
remote peer should be retried on a connection after
receiving a receiver not ready (RNR) error. RNR errors
are generated when a send request arrives before a buffer
has been posted to receive the incoming data. Applies
only to RDMA_PS_TCP.
srq Specifies if the QP associated with the connection is
using a shared receive queue. This field is ignored by
the library if a QP has been created on the rdma_cm_id.
Applies only to RDMA_PS_TCP.
qp_num Specifies the QP number associated with the connection.
This field is ignored by the library if a QP has been
created on the rdma_cm_id. Applies only to RDMA_PS_TCP.
In addition to the connection properties defined above,
InfiniBand QPs are configured with minimum RNR NAK timer and
local ACK timeout values. The minimum RNR NAK timer value is set
to 0, for a delay of 655 ms. The local ACK timeout is calculated
based on the packet lifetime and local HCA ACK delay. The packet
lifetime is determined by the InfiniBand Subnet Administrator and
is part of the resolved route (path record) information. The HCA
ACK delay is a property of the locally used HCA.
Retry count and RNR retry count values are 3-bit values.
The length of the private data provided by the user is limited to
56 bytes for RDMA_PS_TCP, or 180 bytes for RDMA_PS_UDP.
Connections established over iWarp RDMA devices currently require
that the active side of the connection send the first message.
rdma_cm(7), rdma_create_id(3), rdma_resolve_route(3),
rdma_disconnect(3), rdma_listen(3), rdma_get_cm_event(3)
This page is part of the rdma-core (RDMA Core Userspace Libraries
and Daemons) project. Information about the project can be found
at ⟨https://github.com/linux-rdma/rdma-core⟩. If you have a bug
report for this manual page, send it to
linux-rdma@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨https://github.com/linux-rdma/rdma-core.git⟩ on 2023-12-22. (At
that time, the date of the most recent commit that was found in
the repository was 2023-12-20.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
librdmacm 2010-07-19 RDMA_CONNECT(3)
Pages that refer to this page: rdma_create_ep(3), rdma_create_id(3), rdma_disconnect(3), rdma_getaddrinfo(3), rdma_get_cm_event(3), rdma_get_dst_port(3), rdma_get_request(3), rdma_listen(3), rdma_notify(3), rdma_post_read(3), rdma_post_readv(3), rdma_post_send(3), rdma_post_sendv(3), rdma_post_ud_send(3), rdma_post_write(3), rdma_post_writev(3), rdma_resolve_addr(3), rdma_resolve_route(3), rdma_cm(7)
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HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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