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NAME |SYNOPSIS |DESCRIPTION |Polling an extended CQ |RETURN VALUE |NOTES |SEE ALSO |AUTHORS |COLOPHON | |
IBV_CREATE_CQ_EX(3) Libibverbs Programmer's ManualIBV_CREATE_CQ_EX(3)ibv_create_cq_ex - create a completion queue (CQ)
#include <infiniband/verbs.h>struct ibv_cq_ex *ibv_create_cq_ex(struct ibv_context*context,struct ibv_cq_init_attr_ex*cq_attr);
ibv_create_cq_ex()creates a completion queue (CQ) for RDMA device contextcontext. The argumentcq_attr is a pointer to struct ibv_cq_init_attr_ex as defined in <infiniband/verbs.h>. struct ibv_cq_init_attr_ex { int cqe; /* Minimum number of entries required for CQ */ void *cq_context; /* Consumer-supplied context returned for completion events */ struct ibv_comp_channel *channel; /* Completion channel where completion events will be queued. May be NULL if completion events will not be used. */ int comp_vector; /* Completion vector used to signal completion events. Must be >= 0 and < context->num_comp_vectors. */ uint64_t wc_flags; /* The wc_flags that should be returned in ibv_poll_cq_ex. Or'ed bit of enum ibv_wc_flags_ex. */ uint32_t comp_mask; /* compatibility mask (extended verb). */ uint32_t flags /* One or more flags from enum ibv_create_cq_attr_flags */ struct ibv_pd *parent_domain; /* Parent domain to be used by this CQ */ }; enum ibv_wc_flags_ex { IBV_WC_EX_WITH_BYTE_LEN = 1 << 0, /* Require byte len in WC */ IBV_WC_EX_WITH_IMM = 1 << 1, /* Require immediate in WC */ IBV_WC_EX_WITH_QP_NUM = 1 << 2, /* Require QP number in WC */ IBV_WC_EX_WITH_SRC_QP = 1 << 3, /* Require source QP in WC */ IBV_WC_EX_WITH_SLID = 1 << 4, /* Require slid in WC */ IBV_WC_EX_WITH_SL = 1 << 5, /* Require sl in WC */ IBV_WC_EX_WITH_DLID_PATH_BITS = 1 << 6, /* Require dlid path bits in WC */ IBV_WC_EX_WITH_COMPLETION_TIMESTAMP = 1 << 7, /* Require completion device timestamp in WC /* IBV_WC_EX_WITH_CVLAN = 1 << 8, /* Require VLAN info in WC */ IBV_WC_EX_WITH_FLOW_TAG = 1 << 9, /* Require flow tag in WC */ IBV_WC_EX_WITH_COMPLETION_TIMESTAMP_WALLCLOCK = 1 << 11, /* Require completion wallclock timestamp in WC */ }; enum ibv_cq_init_attr_mask { IBV_CQ_INIT_ATTR_MASK_FLAGS = 1 << 0, IBV_CQ_INIT_ATTR_MASK_PD = 1 << 1, }; enum ibv_create_cq_attr_flags { IBV_CREATE_CQ_ATTR_SINGLE_THREADED = 1 << 0, /* This CQ is used from a single threaded, thus no locking is required */ IBV_CREATE_CQ_ATTR_IGNORE_OVERRUN = 1 << 1, /* This CQ will not pass to error state if overrun, CQE always will be written to next entry. * An application must be designed to avoid ever overflowing the CQ, otherwise CQEs might be lost. */ }; In order to poll an extended CQ efficiently, a user could use the following functions.Completion iterator functionsint ibv_start_poll(struct ibv_cq_ex*cq, structibv_poll_cq_attr*attr) Start polling a batch of work completions.attr is given in order to make this function easily extensible in the future. This function either returns 0 on success or an error code otherwise. When no completions are available on the CQ, ENOENT is returned, but the CQ remains in a valid state. On success, querying the completion's attribute could be done using the query functions described below. If an error code is given, end_poll shouldn't be called.int ibv_next_poll(struct ibv_cq_ex*cq) This function is called in order to get the next work completion. It has to be called afterstart_poll and beforeend_poll are called. This function either returns 0 on success or an error code otherwise. When no completions are available on the CQ, ENOENT is returned, but the CQ remains in a valid state. On success, querying the completion's attribute could be done using the query functions described below. If an error code is given, end_poll should still be called, indicating this is the end of the polled batch.void ibv_end_poll(struct ibv_cq_ex*cq) This function indicates the end of polling batch of work completions. After calling this function, the user should start a new batch by callingstart_poll.Polling fields in the completion Below members and functions are used in order to poll the current completion. The current completion is the completion which the iterator points to (start_poll and next_poll advances this iterator). Only fields that the user requested via wc_flags in ibv_create_cq_ex could be queried. In addition, some fields are only valid in certain opcodes and status codes.uint64_t wr_id - Can be accessed directly from structibv_cq_ex.enum ibv_wc_status - Can be accessed directly from structibv_cq_ex.enum ibv_wc_opcode ibv_wc_read_opcode(struct ibv_cq_ex*cq);Get the opcode from the current completion.uint32_t ibv_wc_read_vendor_err(struct ibv_cq_ex*cq);Get the vendor error from the current completion.uint32_t ibv_wc_read_byte_len(struct ibv_cq_ex*cq);Get the payload length from the current completion.__be32 ibv_wc_read_imm_data(struct ibv_cq_ex*cq);Get the immediate data field from the current completion.uint32_t ibv_wc_read_invalidated_rkey(struct ibv_cq_ex*cq);Get the rkey invalided by the SEND_INVAL from the current completion.uint32_t ibv_wc_read_qp_num(struct ibv_cq_ex*cq);Get the QP number field from the current completion.uint32_t ibv_wc_read_src_qp(struct ibv_cq_ex*cq);Get the source QP number field from the current completion.unsigned int ibv_wc_read_wc_flags(struct ibv_cq_ex*cq); Get the QP flags field from the current completion.uint16_t ibv_wc_read_pkey_index(struct ibv_cq_ex*cq);Get the pkey index field from the current completion.uint32_t ibv_wc_read_slid(struct ibv_cq_ex*cq);Get the slid field from the current completion.uint8_t ibv_wc_read_sl(struct ibv_cq_ex*cq);Get the sl field from the current completion.uint8_t ibv_wc_read_dlid_path_bits(struct ibv_cq_ex*cq); Get the dlid_path_bits field from the current completion.uint64_t ibv_wc_read_completion_ts(struct ibv_cq_ex*cq); Get the completion timestamp from the current completion in HCA clock units.uint64_t ibv_wc_read_completion_wallclock_ns(structibv_cq_ex*cq);Get the completion timestamp from the current completion and convert it from HCA clock units to wall clock nanoseconds.uint16_t ibv_wc_read_cvlan(struct ibv_cq_ex*cq);Get the CVLAN field from the current completion.uint32_t ibv_wc_read_flow_tag(struct ibv_cq_ex*cq);Get flow tag from the current completion.void ibv_wc_read_tm_info(struct ibv_cq_ex*cq, structibv_wc_tm_info*tm_info);Get tag matching info from the current completion. struct ibv_wc_tm_info { uint64_t tag; /* tag from TMH */ uint32_t priv; /* opaque user data from TMH */ };ibv_create_cq_ex()returns a pointer to the CQ, or NULL if the request fails.
ibv_create_cq_ex()may create a CQ with size greater than or equal to the requested size. Check the cqe attribute in the returned CQ for the actual size. CQ should be destroyed with ibv_destroy_cq.
ibv_create_cq(3),ibv_destroy_cq(3),ibv_resize_cq(3),ibv_req_notify_cq(3),ibv_ack_cq_events(3),ibv_create_qp(3),ibv_alloc_parent_domain(3)
Matan Barak <matanb@mellanox.com>
This page is part of therdma-core (RDMA Core Userspace Libraries and Daemons) project. Information about the project can be found at ⟨https://github.com/linux-rdma/rdma-core⟩. If you have a bug report for this manual page, send it to linux-rdma@vger.kernel.org. This page was obtained from the project's upstream Git repository ⟨https://github.com/linux-rdma/rdma-core.git⟩ on 2025-08-11. (At that time, the date of the most recent commit that was found in the repository was 2025-08-04.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which isnot part of the original manual page), send a mail to man-pages@man7.orglibibverbs 2016-05-08IBV_CREATE_CQ_EX(3)Pages that refer to this page:mlx5dv_create_cq(3)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |