man/io_uring_submit_and_wait.3

.\" Copyright (C) 2021 Stefan Roesch <shr@fb.com>
.\"
.\" SPDX-License-Identifier: LGPL-2.0-or-later
.\"
.TH io_uring_submit_and_wait 3 "November 15, 2021" "liburing-2.1" "liburing Manual"
.SH NAME
io_uring_submit_and_wait \- submit requests to the submission queue and wait for completion
.SH SYNOPSIS
.nf
.B #include <liburing.h>
.PP
.BI "int io_uring_submit_and_wait(struct io_uring *" ring ","
.BI "                             unsigned " wait_nr ");"
.fi
.SH DESCRIPTION
.PP
The
.BR io_uring_submit_and_wait (3)
function submits the next requests from the submission queue belonging to the
.I ring
and waits for
.I wait_nr
completion events.

After the caller retrieves a submission queue entry (SQE) with
.BR io_uring_get_sqe (3)
and prepares the SQE, it can be submitted with
.BR io_uring_submit_and_wait (3) .

Ideally used with a ring setup with
.BR IORING_SETUP_SINGLE_ISSUER | IORING_SETUP_DEFER_TASKRUN
as that will greatly reduce the number of context switches that an application
will see waiting on multiple requests.

.SH RETURN VALUE
On success
.BR io_uring_submit_and_wait (3)
returns the number of submitted submission queue entries. On failure it returns
.BR -errno .
.SH SEE ALSO
.BR io_uring_queue_init_params (3),
.BR io_uring_get_sqe (3),
.BR io_uring_submit (3),
.BR io_uring_submit_and_wait_timeout (3)