io_uring async workers are split into two types:
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.
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
Returns 0 on success, with values containing the previous values
for the settings. On error, any of the following may be returned.
The kernel was unable to copy the memory pointer to by
values as it was invalid.
-EINVALvalues was NULL or the new values exceeded the maximum
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 email@example.com. This page
was obtained from the project's upstream Git repository
⟨https://github.com/axboe/liburing⟩ on 2023-06-23. (At that
time, the date of the most recent commit that was found in the
repository was 2023-06-22.) 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
liburing-2.2 March 1i3o,_u2r0i2n2g_register_iowq_max_workers(3)