linux/include/uapi
Jens Axboe 6c271ce2f1 io_uring: add submission polling
This enables an application to do IO, without ever entering the kernel.
By using the SQ ring to fill in new sqes and watching for completions
on the CQ ring, we can submit and reap IOs without doing a single system
call. The kernel side thread will poll for new submissions, and in case
of HIPRI/polled IO, it'll also poll for completions.

By default, we allow 1 second of active spinning. This can by changed
by passing in a different grace period at io_uring_register(2) time.
If the thread exceeds this idle time without having any work to do, it
will set:

sq_ring->flags |= IORING_SQ_NEED_WAKEUP.

The application will have to call io_uring_enter() to start things back
up again. If IO is kept busy, that will never be needed. Basically an
application that has this feature enabled will guard it's
io_uring_enter(2) call with:

read_barrier();
if (*sq_ring->flags & IORING_SQ_NEED_WAKEUP)
	io_uring_enter(fd, 0, 0, IORING_ENTER_SQ_WAKEUP);

instead of calling it unconditionally.

It's mandatory to use fixed files with this feature. Failure to do so
will result in the application getting an -EBADF CQ entry when
submitting IO.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-02-28 08:24:23 -07:00
..
asm-generic io_uring: add support for pre-mapped user IO buffers 2019-02-28 08:24:23 -07:00
drm drm/msm: add uapi to get/set debug name 2018-12-11 13:07:05 -05:00
linux io_uring: add submission polling 2019-02-28 08:24:23 -07:00
misc
mtd ubi: expose the volume CRC check skip flag 2018-08-15 00:25:21 +02:00
rdma RDMA/hns: Update the kernel header file of hns 2019-01-25 09:55:48 -07:00
scsi scsi: ufs: fix integer type usage in uapi header 2018-10-15 22:44:30 -04:00
sound ALSA: firewire-tascam: notify events of change of state for userspace applications 2018-11-23 15:31:15 +01:00
video
xen xen/gntdev: Add initial support for dma-buf UAPI 2018-07-26 23:05:14 -04:00