NAME

       io_uring_register_iowq_max_workers - modify the maximum allowed async workers

SYNOPSIS

       #include <liburing.h>

       int io_uring_register_iowq_max_workers(struct io_uring *ring,
                                              unsigned int *values);

DESCRIPTION

       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.

RETURN VALUE

       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.

SEE ALSO

       io_uring_queue_init(3), io_uring_register(2)

liburing-2.2                                     March 13, 2022            io_uring_register_iowq_max_workers(3)