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io_uring_for_each_cqe(3) — Linux manual page

io_uring_for_each_cqe(3)     liburing Manualio_uring_for_each_cqe(3)

NAME        top

       io_uring_for_each_cqe - iterate pending completion events

SYNOPSIS        top

#include <liburing.h>io_uring_for_each_cqe(struct io_uring *ring,unsignedhead,struct io_uring_cqe *cqe) { }

DESCRIPTION        top

       Theio_uring_for_each_cqe(3) is a macro helper that iterates       completion events belonging to thering usinghead as a temporary       iterator, and pointscqe to each pending event when iterating.       This helper provides an efficient way to iterate all pending       events in the ring, and then advancing the CQ ring by callingio_uring_cq_advance(3) with the number of CQEs consumed when done.       As updating the kernel visible CQ ring state involves an ordered       write, doing it once for a number of events is more efficient than       handling each completion separately and callingio_uring_cqe_seen(3) for each of them.

EXAMPLE        top

       void handle_cqes(struct io_uring *ring)       {            struct io_uring_cqe *cqe;            unsigned head;            unsigned i = 0;            io_uring_for_each_cqe(ring, head, cqe) {                 /* handle completion */                 printf("cqe: %d\n", cqe->res);                 i++;            }            io_uring_cq_advance(ring, i);       }

RETURN VALUE        top

       None

SEE ALSO        top

io_uring_wait_cqe_timeout(3),io_uring_wait_cqe(3),io_uring_wait_cqes(3),io_uring_cqe_seen(3),io_uring_buf_ring_cq_advance(3)

COLOPHON        top

       This page is part of theliburing (A library for io_uring)       project.  Information about the project can be found at        ⟨https://github.com/axboe/liburing⟩.  If you have a bug report for       this manual page, send it to io-uring@vger.kernel.org.  This page       was obtained from the project's upstream Git repository       ⟨https://github.com/axboe/liburing⟩ on 2025-08-11.  (At that time,       the date of the most recent commit that was found in the       repository was 2025-08-02.)  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.orgliburing-2.4                  June 04, 2023io_uring_for_each_cqe(3)

Pages that refer to this page:io_uring_for_each_cqe(3), io_uring_wait_cqes(3)

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