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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | COLOPHON |
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io_uring_re...max_workers(3) liburing Manual io_uring_re...max_workers(3)
io_uring_register_iowq_max_workers - modify the maximum allowed
async workers
#include <liburing.h>
int io_uring_register_iowq_max_workers(struct io_uring *ring,
unsigned int *values);
io_uring async workers are split into two types:
Bounded
These workers have a bounded execution time. Examples of
that are filesystem reads, which normally complete in a
relatively short amount of time. In case of disk failures,
they are still bounded by a timeout operation that will
abort them if exceeded.
Unbounded
Work items here may take an indefinite amount of time to
complete. Examples include doing IO to sockets, pipes, or
any other non-regular type of file.
By default, the amount of bounded IO workers is limited to how
many SQ entries the ring was setup with, or 4 times the number of
online CPUs in the system, whichever is smaller. Unbounded workers
are only limited by the process task limit, as indicated by the
rlimit RLIMIT_NPROC limit.
This can be modified by calling io_uring_register_iowq_max_workers
with ring set to the ring in question, and values pointing to an
array of two values. The first element should contain the number
of desired bounded workers, and the second element should contain
the number of desired unbounded workers. These are both maximum
values, io_uring will not maintain a high count of idle workers,
they are reaped when they are not necessary anymore.
If called with both values set to 0, the existing values are
returned.
Returns 0 on success, with values containing the previous values
for the settings. On error, any of the following may be returned.
-EFAULT
The kernel was unable to copy the memory pointer to by
values as it was invalid.
-EINVAL
values was NULL or the new values exceeded the maximum
allowed value.
io_uring_queue_init(3), io_uring_register(2)
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 2025-08-11. (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 is not part of the original manual page), send a mail to
man-pages@man7.org
liburing-2.2 March 13, 2022 io_uring_re...max_workers(3)
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HTML rendering created 2025-09-06 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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