struct ibv_send_wr {
	uint64_t                wr_id;
	struct ibv_send_wr     *next;
	struct ibv_sge         *sg_list;
	int                     num_sge;
	enum ibv_wr_opcode      opcode;
	int                     send_flags;
	uint32_t                imm_data;
	union {
		struct {
		       uint64_t        remote_addr;
		       uint32_t        rkey;
		} rdma;
		struct {
		        uint64_t        remote_addr;
		        uint64_t        compare_add;
		        uint64_t        swap;
		        uint32_t        rkey;
		} atomic;
		struct {
		       	struct ibv_ah  *ah;
		       	uint32_t        remote_qpn;
		       	uint32_t        remote_qkey;
		} ud;
	} wr;
};