io_uring_register_buffers - Man Page

register buffers for fixed buffer operations

Synopsis

#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);

Description

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.

Return Value

On success io_uring_register_buffers(3) and io_uring_register_buffers_sparse(3) return 0. On failure they return -errno.

See Also

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)

Referenced By

io_uring_prep_read_fixed(3), io_uring_prep_write_fixed(3), io_uring_register_buffers(3), io_uring_sqe_set_flags(3), io_uring_unregister_buffers(3).

November 15, 2021 liburing-2.1 liburing Manual