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NAME | SYNOPSIS | DESCRIPTION | NOTES | RETURN VALUE | SEE ALSO | COLOPHON |
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io_uring_register_ring_fd(3) liburing Manual io_uring_register_ring_fd(3)
io_uring_register_ring_fd - register a ring file descriptor
#include <liburing.h>
int io_uring_register_ring_fd(struct io_uring *ring);
io_uring_register_ring_fd(3) registers the file descriptor of the
ring.
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.
Available since kernel 5.18.
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 fd.
Returns 1 on success, indicating that one file descriptor was
registered, or -errno on error.
io_uring_unregister_ring_fd(3), io_uring_register_files(3)
This page is part of the liburing (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 2025-02-02. (At that time,
the date of the most recent commit that was found in the
repository was 2025-01-22.) 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
man-pages@man7.org
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)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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