io_uring_set_iowait(3)          liburing Manual         io_uring_set_iowait(3)

NAME
       io_uring_set_iowait - toggle of iowait usage when waiting on CQEs

SYNOPSIS
       #include <liburing.h>

       int io_uring_set_iowait(struct io_uring *ring,
                               bool enable_iowait);

DESCRIPTION
       By default, io_uring marks a waiting task as being in iowait if it's
       sleeping waiting on events and there are pending requests. This isn't
       necessarily always useful, and may be confusing on non-storage setups
       where iowait isn't expected. It can also cause extra power usage by
       preventing the CPU from entering lower sleep states.

       The io_uring_set_iowait(3) function allows the user to toggle this
       behavior. If enable_iowait is set to true, the iowait behavior is
       enabled. If it is set to false, the iowait behavior is disabled. The
       iowait behavior is enabled by default when a ring is created.

       If the iowait is disabled, the submit functions will set
       IORING_ENTER_NO_IOWAIT in the flags argument to io_uring_enter(2).

       If the kernel supports this feature, it will be marked by having the
       IORING_FEAT_NO_IOWAIT feature flag set.

       Available since kernel 6.15.



RETURN VALUE
       On success, io_uring_set_iowait(3) returns 0. On failure, it returns
       -EOPNOTSUPP.



SEE ALSO
       io_uring_enter(2), io_uring_submit(3), io_uring_submit_and_wait(3)

liburing-2.12                    July 27, 2025          io_uring_set_iowait(3)