ibv_create_qp (3)

NAME

ibv_create_qp, ibv_destroy_qp - create or destroy a queue pair (QP)

SYNOPSIS

#include <infiniband/verbs.h>

struct ibv_qp *ibv_create_qp(struct ibv_pd *pd,
                             struct ibv_qp_init_attr *qp_init_attr);

int ibv_destroy_qp(struct ibv_qp *qp);

DESCRIPTION

ibv_create_qp() creates a queue pair (QP) associated with the protection domain pd. The argument qp_init_attr is an ibv_qp_init_attr struct, as defined in <infiniband/verbs.h>.

struct ibv_qp_init_attr {
void                   *qp_context;     /* Associated context of the QP */
struct ibv_cq          *send_cq;        /* CQ to be associated with the Send Queue (SQ) */ 
struct ibv_cq          *recv_cq;        /* CQ to be associated with the Receive Queue (RQ) */
struct ibv_srq         *srq;            /* SRQ handle if QP is to be associated with an SRQ, otherwise NULL */
struct ibv_qp_cap       cap;            /* QP capabilities */
enum ibv_qp_type        qp_type;        /* QP Transport Service Type: IBV_QPT_RC, IBV_QPT_UC, IBV_QPT_UD or IBV_QPT_RAW_PACKET */
int                     sq_sig_all;     /* If set, each Work Request (WR) submitted to the SQ generates a completion entry */
};

struct ibv_qp_cap {
uint32_t                max_send_wr;    /* Requested max number of outstanding WRs in the SQ */
uint32_t                max_recv_wr;    /* Requested max number of outstanding WRs in the RQ */
uint32_t                max_send_sge;   /* Requested max number of scatter/gather (s/g) elements in a WR in the SQ */
uint32_t                max_recv_sge;   /* Requested max number of s/g elements in a WR in the SQ */
uint32_t                max_inline_data;/* Requested max number of data (bytes) that can be posted inline to the SQ, otherwise 0 */
};

The function ibv_create_qp() will update the qp_init_attr->cap struct with the actual

values of the QP that was created; the values will be greater than or equal to the values requested.

ibv_destroy_qp() destroys the QP qp.

RETURN VALUE

ibv_create_qp() returns a pointer to the created QP, or NULL if the request fails. Check the QP number (qp_num) in the returned QP.

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

NOTES

ibv_create_qp() will fail if a it is asked to create QP of a type other than IBV_QPT_RC or IBV_QPT_UD associated with an SRQ.

The attributes max_recv_wr and max_recv_sge are ignored by ibv_create_qp() if the QP is to be associated with an SRQ.

ibv_destroy_qp() fails if the QP is attached to a multicast group.

SEE ALSO

ibv_alloc_pd(3), ibv_modify_qp(3), ibv_query_qp(3)

AUTHORS

Dotan Barak <dotanba@gmail.com>