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IBV_POST_SEND(3) Libibverbs Programmer's Manual IBV_POST_SEND(3)


ibv_post_send - post a list of work requests (WRs) to a send queue


#include <infiniband/verbs.h>

int ibv_post_send(struct ibv_qp *qp, struct ibv_send_wr *wr,
                  struct ibv_send_wr **bad_wr);


ibv_post_send() posts the linked list of work requests (WRs) starting with wr to the send queue of the queue pair qp. It stops processing WRs from this list at the first failure (that can be detected immediately while requests are being posted), and returns this failing WR through bad_wr.

The argument wr is an ibv_send_wr struct, as defined in <infiniband/verbs.h>.

struct ibv_send_wr {

uint64_t wr_id; /* User defined WR ID */ struct ibv_send_wr *next; /* Pointer to next WR in list, NULL if last WR */ struct ibv_sge *sg_list; /* Pointer to the s/g array */ int num_sge; /* Size of the s/g array */ enum ibv_wr_opcode opcode; /* Operation type */ unsigned int send_flags; /* Flags of the WR properties */ union {
__be32 imm_data; /* Immediate data (in network byte order) */ uint32_t invalidate_rkey; /* Remote rkey to invalidate */
}; union {
struct {
uint64_t remote_addr; /* Start address of remote memory buffer */ uint32_t rkey; /* Key of the remote Memory Region */
} rdma; struct {
uint64_t remote_addr; /* Start address of remote memory buffer */ uint64_t compare_add; /* Compare operand */ uint64_t swap; /* Swap operand */ uint32_t rkey; /* Key of the remote Memory Region */
} atomic; struct {
struct ibv_ah *ah; /* Address handle (AH) for the remote node address */ uint32_t remote_qpn; /* QP number of the destination QP */ uint32_t remote_qkey; /* Q_Key number of the destination QP */
} ud;
} wr; union {
struct {
uint32_t remote_srqn; /* Number of the remote SRQ */
} xrc;
} qp_type; union {
struct {
struct ibv_mw *mw; /* Memory window (MW) of type 2 to bind */ uint32_t rkey; /* The desired new rkey of the MW */ struct ibv_mw_bind_info bind_info; /* MW additional bind information */
} bind_mw; struct {
void *hdr; /* Pointer address of inline header */ uint16_t hdr_sz; /* Inline header size */ uint16_t mss; /* Maximum segment size for each TSO fragment */
} tso;

struct ibv_mw_bind_info {

struct ibv_mr *mr; /* The Memory region (MR) to bind the MW to */ uint64_t addr; /* The address the MW should start at */ uint64_t length; /* The length (in bytes) the MW should span */ unsigned int mw_access_flags; /* Access flags to the MW. Use ibv_access_flags */

struct ibv_sge {

uint64_t addr; /* Start address of the local memory buffer or number of bytes from the
start of the MR for MRs which are IBV_ZERO_BASED */ uint32_t length; /* Length of the buffer */ uint32_t lkey; /* Key of the local Memory Region */

Each QP Transport Service Type supports a specific set of opcodes, as shown in the following table:

IBV_WR_SEND                 |     X      |     X      |     X      |         X        |         X
IBV_WR_SEND_WITH_IMM        |     X      |     X      |     X      |         X        |
IBV_WR_RDMA_WRITE           |            |     X      |     X      |         X        |
IBV_WR_RDMA_WRITE_WITH_IMM  |            |     X      |     X      |         X        |
IBV_WR_RDMA_READ            |            |            |     X      |         X        |
IBV_WR_ATOMIC_CMP_AND_SWP   |            |            |     X      |         X        |
IBV_WR_ATOMIC_FETCH_AND_ADD |            |            |     X      |         X        |
IBV_WR_LOCAL_INV            |            |     X      |     X      |         X        |
IBV_WR_BIND_MW              |            |     X      |     X      |         X        |
IBV_WR_SEND_WITH_INV        |            |     X      |     X      |         X        |
IBV_WR_TSO                  |     X      |            |            |                  |         X

The attribute send_flags describes the properties of the WR. It is either 0 or the bitwise OR of one or more of the following flags:

in a send WQE. Valid only for Send and RDMA Write. The L_Key will not be checked.
Valid only when device_cap_flags in device_attr indicates current QP is supported by checksum offload.


ibv_post_send() returns 0 on success, or the value of errno on failure (which indicates the failure reason).


The user should not alter or destroy AHs associated with WRs until request is fully executed and a work completion has been retrieved from the corresponding completion queue (CQ) to avoid unexpected behavior.

The buffers used by a WR can only be safely reused after WR the request is fully executed and a work completion has been retrieved from the corresponding completion queue (CQ). However, if the IBV_SEND_INLINE flag was set, the buffer can be reused immediately after the call returns.

IBV_WR_DRIVER1 is an opcode that should be used to issue a specific driver operation.


ibv_create_qp(3), ibv_create_ah(3), ibv_post_recv(3), ibv_post_srq_recv(3), ibv_poll_cq(3)


2006-10-31 libibverbs