io_uring_register_ring_fd(3) — Linux manual page


io_uring_register_ring_fd(3) liburing Manualio_uring_register_ring_fd(3)

NAME         top

       io_uring_register_ring_fd - register a ring file descriptor

SYNOPSIS         top

       #include <liburing.h>

       int io_uring_register_ring_fd(struct io_uring *ring);

DESCRIPTION         top

       io_uring_register_ring_fd(3) registers the file descriptor of the

       Whenever io_uring_enter(2) is called to submit request or wait
       for completions, the kernel must grab a reference to the file
       descriptor. If the application using io_uring is threaded, the
       file table is marked as shared, and the reference grab and put of
       the file descriptor count is more expensive than it is for a non-
       threaded application.

       Similarly to how io_uring allows registration of files, this
       allow registration of the ring file descriptor itself. This
       reduces the overhead of the io_uring_enter(2) system call.

       If an application using liburing is threaded, then an application
       should call this function to register the ring descriptor when a
       ring is set up. See NOTES for restrictions when a ring is shared.

NOTES         top

       When the ring descriptor is registered, it is stored internally
       in the struct io_uring structure. For applications that share a
       ring between threads, for example having one thread do submits
       and another reap events, then this optimization cannot be used as
       each thread may have a different index for the registered ring

RETURN VALUE         top

       Returns 1 on success, indicating that one file descriptor was
       registered, or -errno on error.

SEE ALSO         top

       io_uring_unregister_ring_fd(3), io_uring_register_files(3)

COLOPHON         top

       This page is part of the liburing (A library for io_uring)
       project.  Information about the project can be found at 
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       this manual page, send it to  This page
       was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-06-23.  (At that
       time, the date of the most recent commit that was found in the
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liburing-2.2                 March 11, 2022 io_uring_register_ring_fd(3)

Pages that refer to this page: io_uring_close_ring_fd(3)io_uring_queue_init(3)io_uring_queue_init_mem(3)io_uring_queue_init_params(3)io_uring_register_ring_fd(3)io_uring_unregister_ring_fd(3)