Copyright (C) 2021 Stefan Roesch <[email protected]>

SPDX-License-Identifier: LGPL-2.0-or-later

io_uring_register_buffers - register buffers for fixed buffer operations

 #include <liburing.h> 

 "int io_uring_register_buffers(struct io_uring *" ring ",  " const struct iovec *" iovecs ",  " unsigned " nr_iovecs ");" 

 "int io_uring_register_buffers_sparse(struct io_uring *" ring ",  " unsigned " nr_iovecs ");" 

The io_uring_register_buffers (3) function registers nr_iovecs number of buffers defined by the array iovecs belonging to the ring . The io_uring_register_buffers_sparse (3) function registers nr_iovecs empty buffers belonging to the ring . These buffers must be updated before use, using eg io_uring_register_buffers_update_tag (3). After the caller has registered the buffers, they can be used with one of the fixed buffers functions. Registered buffers is an optimization that is useful in conjunction with O_DIRECT reads and writes, where it maps the specified range into the kernel once when the buffer is registered rather than doing a map and unmap for each IO every time IO is performed to that region. Additionally, it also avoids manipulating the page reference counts for each IO.

On success io_uring_register_buffers (3) and io_uring_register_buffers_sparse (3) return 0. On failure they return -errno . io_uring_get_sqe (3), io_uring_unregister_buffers (3), io_uring_register_buf_ring (3), io_uring_prep_read_fixed (3), io_uring_prep_write_fixed (3)