84 lines
4.1 KiB
Groff
84 lines
4.1 KiB
Groff
.TH "RDMA_CONNECT" 3 "2007-10-31" "librdmacm" "Librdmacm Programmer's Manual" librdmacm
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.SH NAME
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rdma_connect \- Initiate an active connection request.
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.SH SYNOPSIS
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.B "#include <rdma/rdma_cma.h>"
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.P
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.B "int" rdma_connect
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.BI "(struct rdma_cm_id *" id ","
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.BI "struct rdma_conn_param *" conn_param ");"
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.SH ARGUMENTS
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.IP "id" 12
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RDMA identifier.
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.IP "conn_param" 12
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connection parameters. See CONNECTION PROPERTIES below for details.
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.SH "DESCRIPTION"
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For an rdma_cm_id of type RDMA_PS_TCP, this call initiates a connection request
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to a remote destination. For an rdma_cm_id of type RDMA_PS_UDP, it initiates
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a lookup of the remote QP providing the datagram service.
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.SH "NOTES"
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Users must have resolved a route to the destination address
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by having called rdma_resolve_route before calling this routine.
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.SH "CONNECTION PROPERTIES"
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The following properties are used to configure the communication and specified
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by the conn_param parameter when connecting or establishing datagram
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communication.
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.IP private_data
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References a user-controlled data buffer. The contents of the buffer are
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copied and transparently passed to the remote side as part of the
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communication request. May be NULL if private_data is not required.
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.IP private_data_len
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Specifies the size of the user-controlled data buffer. Note that the actual
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amount of data transferred to the remote side is transport dependent and may
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be larger than that requested.
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.IP responder_resources
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The maximum number of outstanding RDMA read and atomic operations that the
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local side will accept from the remote side. Applies only to RDMA_PS_TCP.
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This value must be less than or equal to the local RDMA device attribute
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max_qp_rd_atom and remote RDMA device attribute max_qp_init_rd_atom. The
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remote endpoint can adjust this value when accepting the connection.
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.IP initiator_depth
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The maximum number of outstanding RDMA read and atomic operations that the
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local side will have to the remote side. Applies only to RDMA_PS_TCP.
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This value must be less than or equal to the local RDMA device attribute
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max_qp_init_rd_atom and remote RDMA device attribute max_qp_rd_atom. The
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remote endpoint can adjust this value when accepting the connection.
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.IP flow_control
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Specifies if hardware flow control is available. This value is exchanged
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with the remote peer and is not used to configure the QP. Applies only to
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RDMA_PS_TCP.
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.IP retry_count
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The maximum number of times that a data transfer operation should be retried
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on the connection when an error occurs. This setting controls the number of
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times to retry send, RDMA, and atomic operations when timeouts occur.
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Applies only to RDMA_PS_TCP.
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.IP rnr_retry_count
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The maximum number of times that a send operation from the remote peer
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should be retried on a connection after receiving a receiver not ready (RNR)
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error. RNR errors are generated when a send request arrives before a buffer
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has been posted to receive the incoming data. Applies only to RDMA_PS_TCP.
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.IP srq
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Specifies if the QP associated with the connection is using a shared receive
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queue. This field is ignored by the library if a QP has been created on the
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rdma_cm_id. Applies only to RDMA_PS_TCP.
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.IP qp_num
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Specifies the QP number associated with the connection. This field is ignored
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by the library if a QP has been created on the rdma_cm_id. Applies only to
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RDMA_PS_TCP.
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.SH "INFINIBAND SPECIFIC"
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In addition to the connection properties defined above, InfiniBand QPs are
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configured with minimum RNR NAK timer and local ACK timeout values. The
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minimum RNR NAK timer value is set to 0, for a delay of 655 ms.
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The local ACK timeout is calculated based on the packet lifetime and local
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HCA ACK delay. The packet lifetime is determined by the InfiniBand Subnet
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Administrator and is part of the resolved route (path record) information.
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The HCA ACK delay is a property of the locally used HCA.
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.P
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Retry count and RNR retry count values are 3-bit values.
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.SH "IWARP SPECIFIC"
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Connections established over iWarp RDMA devices currently require that the
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active side of the connection send the first message.
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.SH "SEE ALSO"
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rdma_cm(7), rdma_create_id(3), rdma_resolve_route(3), rdma_disconnect(3),
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rdma_listen(3), rdma_get_cm_event(3)
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