1IBV_POST_SRQ_OPS(3) Libibverbs Programmer's Manual IBV_POST_SRQ_OPS(3)
2
6 ibv_post_srq_ops - perform on a special shared receive queue (SRQ) con‐
7 figuration manipulations
8
10 #include <infiniband/verbs.h>
11 int ibv_post_srq_ops(struct ibv_srq *srq, struct ibv_ops_wr *wr,
13 struct ibv_ops_wr **bad_wr);
14
16 The ibv_post_srq_ops() performs series of offload configuration manipu‐
17 lations on special types of SRQ srq. Currenlty it is used to configure
18 tag matching SRQ. Series of configuration operations defined by linked
19 lists of struct ibv_ops_wr elements starting from wr.
20 struct ibv_ops_wr {
22 uint64_t wr_id; /* User defined WR ID */
23 /* Pointer to next WR in list, NULL if last WR */
24 struct ibv_ops_wr *next;
25 enum ibv_ops_wr_opcode opcode; /* From enum ibv_ops_wr_opcode */
26 int flags; /* From enum ibv_ops_flags */
27 struct {
28 /* Number of unexpected messages
29 * handled by SW */
30 uint32_t unexpected_cnt;
31 /* Input parameter for the DEL opcode
32 * and output parameter for the ADD opcode */
33 uint32_t handle;
34 struct {
35 uint64_t recv_wr_id; /* User defined WR ID for TM_RECV */
36 struct ibv_sge *sg_list; /* Pointer to the s/g array */
37 int num_sge; /* Size of the s/g array */
38 uint64_t tag;
39 uint64_t mask; /* Incoming message considered matching if
40 TMH.tag & entry.mask == entry.tag */
41 } add;
42 } tm;
43 };
44 First part of struct ibv_ops_wr retains ibv_send_wr notion. Opcode
46 defines operation to perform. Currently supported IBV_WR_TAG_ADD,
47 IBV_WR_TAG_DEL and IBV_WR_TAG_SYNC values. See below for detailed
48 description.
49 To allow reliable data delivery TM SRQ maintains special low level syn‐
51 chronization primitive - phase synchronization. Receive side message
52 handling comprises two concurrent activities - posting tagged buffers
53 by SW and receiving incoming messages by HW. This process considered
54 coherent only if all unexpected messages received by HW is completely
55 processed in SW. To pass to hardware number of processed unexpected
56 messages unexpected_cnt field should be used and IBV_OPS_TM_SYNC flag
57 should be set.
58 To request WC for tag list operations IBV_OPS_SIGNALED flags should be
60 passed. In this case WC will be generated on TM SRQ's CQ, provided
61 wr_id will identify WC.
62 Opcode IBV_WR_TAG_ADD used to add tag entry to tag matching list. Tag
64 entry consists of SGE list, tag & mask (matching parameters), user
65 specified opaque wr_id (passed via recv_wr_id field) and uniquely iden‐
66 tified by handle (returned by driver). Size of tag matching list is
67 limited by max_num_tags. SGE list size is limited by max_sge.
68 Opcode IBV_WR_TAG_DEL removes previously added tag entry. Field handle
70 should be set to value returned by previously performed IBV_WR_TAG_ADD
71 operation. Operation may fail due to concurrent tag consumption - in
72 this case IBV_WC_TM_ERR status will be returned in WC.
73 Opcode IBV_WR_TAG_SYNC may be used if no changes to matching list
75 required, just to updated unexpected messages counter.
76 IBV_WC_TM_SYNC_REQ flag returned in list operation WC shows that
78 counter synchronization required. This flag also may be returned by
79 unexpected receive WC, asking for IBV_WR_TAG_SYNC operation to keep TM
80 coherence consistency.
81
83 ibv_post_srq_ops() returns 0 on success, or the value of errno on fail‐
84 ure (which indicates the failure reason).
85
87 ibv_create_srq_ex(3),
88
90 Artemy Kovalyov <artemyko@mellanox.com>
91libibverbs 2017-03-26 IBV_POST_SRQ_OPS(3)