io_uring_for_each_cqe(3) — Linux manual page


io_uring_for_each_cqe(3)     liburing Manual    io_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,
                             unsigned head,
                             struct io_uring_cqe *cqe) { }

DESCRIPTION         top

       The io_uring_for_each_cqe(3) is a macro helper that iterates
       completion events belonging to the ring using head as a temporary
       iterator, and points cqe 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 calling
       io_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 calling
       io_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);

            io_uring_cq_advance(ring, i);

RETURN VALUE         top


SEE ALSO         top

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

COLOPHON         top

       This page is part of the liburing (A library for io_uring)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for
       this manual page, send it to  This page
       was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2023-12-19.)  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 is not part of the original manual page), send a mail to

liburing-2.4                  June 04, 2023     io_uring_for_each_cqe(3)

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