1IBV_POLL_CQ(3)          Libibverbs Programmer's Manual          IBV_POLL_CQ(3)
2
3
4

NAME

6       ibv_poll_cq - poll a completion queue (CQ)
7

SYNOPSIS

9       #include <infiniband/verbs.h>
10
11       int ibv_poll_cq(struct ibv_cq *cq, int num_entries,
12                       struct ibv_wc *wc);
13

DESCRIPTION

15       ibv_poll_cq()  polls  the  CQ  cq  for work completions and returns the
16       first num_entries (or all available  completions  if  the  CQ  contains
17       fewer  than this number) in the array wc.  The argument wc is a pointer
18       to an array of ibv_wc structs, as defined in <infiniband/verbs.h>.
19
20       struct ibv_wc {
21               uint64_t                wr_id;          /* ID of the completed Work Request (WR) */
22               enum ibv_wc_status      status;         /* Status of the operation */
23               enum ibv_wc_opcode      opcode;         /* Operation type specified in the completed WR */
24               uint32_t                vendor_err;     /* Vendor error syndrome */
25               uint32_t                byte_len;       /* Number of bytes transferred */
26               union {
27                       __be32                  imm_data;         /* Immediate data (in network byte order) */
28                       uint32_t                invalidated_rkey; /* Local RKey that was invalidated */
29               };
30               uint32_t                qp_num;         /* Local QP number of completed WR */
31               uint32_t                src_qp;         /* Source QP number (remote QP number) of completed WR (valid only for UD QPs) */
32               unsigned int            wc_flags;       /* Flags of the completed WR */
33               uint16_t                pkey_index;     /* P_Key index (valid only for GSI QPs) */
34               uint16_t                slid;           /* Source LID */
35               uint8_t                 sl;             /* Service Level */
36               uint8_t                 dlid_path_bits; /* DLID path bits (not applicable for multicast messages) */
37       };
38
39
40       The attribute wc_flags describes the properties of the work completion.
41       It is either 0 or the bitwise OR of one or more of the following flags:
42
43       IBV_WC_GRH  GRH is present (valid only for UD QPs)
44
45       IBV_WC_WITH_IMM  Immediate data value is valid
46
47       IBV_WC_WITH_INV   Invalidated  RKey data value is valid (cannot be com‐
48       bined with IBV_WC_WITH_IMM)
49
50       IBV_WC_IP_CSUM_OK  TCP/UDP checksum over IPv4 and IPv4 header  checksum
51       are
52              verified.  Valid only when device_cap_flags in device_attr indi‐
53              cates current QP is supported by checksum offload.
54
55       Not all wc attributes are always valid. If  the  completion  status  is
56       other  than  IBV_WC_SUCCESS,  only  the following attributes are valid:
57       wr_id, status, qp_num, and vendor_err.
58

RETURN VALUE

60       On success, ibv_poll_cq() returns a non-negative  value  equal  to  the
61       number of completions found.  On failure, a negative value is returned.
62

NOTES

64       Each polled completion is removed from the CQ and cannot be returned to
65       it.
66
67       The user should consume work completions at a  rate  that  prevents  CQ
68       overrun  from  occurrence.   In  case  of a CQ overrun, the async event
69       IBV_EVENT_CQ_ERR will be triggered, and the CQ cannot be used.
70
71       IBV_WC_DRIVER1 will be reported as a response to IBV_WR_DRIVER1 opcode.
72

SEE ALSO

74       ibv_post_send(3), ibv_post_recv(3)
75

AUTHORS

77       Dotan Barak <dotanba@gmail.com>
78
79
80
81libibverbs                        2006-10-31                    IBV_POLL_CQ(3)
Impressum