rdma_accept(3)

1RDMA_ACCEPT(3)           Librdmacm Programmer's Manual          RDMA_ACCEPT(3)
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NAME

6       rdma_accept - Called to accept a connection request.
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SYNOPSIS

9       #include <rdma/rdma_cma.h>
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11       int   rdma_accept   (struct   rdma_cm_id  *id,  struct  rdma_conn_param
12       *conn_param);
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ARGUMENTS

15       id          Connection identifier associated with the request.
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17       conn_param  Information needed to establish the connection.   See  CON‐
18                   NECTION PROPERTIES below for details.
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DESCRIPTION

21       Called  from the listening side to accept a connection or datagram ser‐
22       vice lookup request.
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NOTES

25       Unlike the socket accept routine, rdma_accept is not called on  a  lis‐
26       tening  rdma_cm_id.  Instead, after calling rdma_listen, the user waits
27       for  an  RDMA_CM_EVENT_CONNECT_REQUEST  event  to  occur.    Connection
28       request  events  give the user a newly created rdma_cm_id, similar to a
29       new socket, but the rdma_cm_id is bound  to  a  specific  RDMA  device.
30       rdma_accept is called on the new rdma_cm_id.
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CONNECTION PROPERTIES

33       The  following  properties  are used to configure the communication and
34       specified by the conn_param parameter when accepting  a  connection  or
35       datagram  communication  request.  Users should use the rdma_conn_param
36       values reported in the connection request event to determine  appropri‐
37       ate  values  for  these fields when accepting.  Users may reference the
38       rdma_conn_param structure in the connection event directly, or can ref‐
39       erence  their  own structure.  If the rdma_conn_param structure from an
40       event is referenced, the event must not be acked until after this  call
41       returns.
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43       private_data
44              References  a  user-controlled data buffer.  The contents of the
45              buffer are copied and transparently passed to the remote side as
46              part  of the communication request.  May be NULL if private_data
47              is not required.
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49       private_data_len
50              Specifies the size of the  user-controlled  data  buffer.   Note
51              that the actual amount of data transferred to the remote side is
52              transport dependent and may be larger than that requested.
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54       responder_resources
55              The maximum number of outstanding RDMA read  and  atomic  opera‐
56              tions  that  the  local  side  will accept from the remote side.
57              Applies only to RDMA_PS_TCP.  This value must be  less  than  or
58              equal  to the local RDMA device attribute max_qp_rd_atom and the
59              responder_resources value reported in the connect request event.
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61       initiator_depth
62              The maximum number of outstanding RDMA read  and  atomic  opera‐
63              tions that the local side will have to the remote side.  Applies
64              only to RDMA_PS_TCP.  This value must be less than or  equal  to
65              the local RDMA device attribute max_qp_init_rd_atom and the ini‐
66              tiator_depth value reported in the connect request event.
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68       flow_control
69              Specifies if hardware flow control is available.  This value  is
70              exchanged  with the remote peer and is not used to configure the
71              QP.  Applies only to RDMA_PS_TCP.
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73       retry_count
74              This value is ignored.
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76       rnr_retry_count
77              The maximum number of times  that  a  send  operation  from  the
78              remote  peer should be retried on a connection after receiving a
79              receiver not ready (RNR) error.  RNR errors are generated when a
80              send  request arrives before a buffer has been posted to receive
81              the incoming data.  Applies only to RDMA_PS_TCP.
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83       srq    Specifies if the QP associated with the connection  is  using  a
84              shared receive queue.  This field is ignored by the library if a
85              QP  has  been  created  on  the  rdma_cm_id.   Applies  only  to
86              RDMA_PS_TCP.
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88       qp_num Specifies  the  QP  number associated with the connection.  This
89              field is ignored by the library if a QP has been created on  the
90              rdma_cm_id.
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INFINIBAND SPECIFIC

93       In  addition to the connection properties defined above, InfiniBand QPs
94       are configured with minimum RNR NAK timer and local ACK timeout values.
95       The  minimum  RNR  NAK  timer value is set to 0, for a delay of 655 ms.
96       The local ACK timeout is calculated based on the  packet  lifetime  and
97       local  HCA ACK delay.  The packet lifetime is determined by the Infini‐
98       Band Subnet Administrator and is part of the route (path record) infor‐
99       mation  obtained  by  the  active  side of the connection.  The HCA ACK
100       delay is a property of the locally used HCA.
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102       The RNR retry count is a 3-bit value.
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