IO_SETUP(2) (2020-12-21) IO_SETUP(2)
NAME
io_setup - create an asynchronous I/O context
SYNOPSIS
#include <linux/aio_abi.h> /* Defines needed types */
long io_setup(unsigned nr_events, aio_context_t *ctx_idp);
Note: There is no glibc wrapper for this system call; see
NOTES.
DESCRIPTION
Note: this page describes the raw Linux system call inter-
face. The wrapper function provided by libaio uses a dif-
ferent type for the ctx_idp argument. See NOTES.
The io_setup() system call creates an asynchronous I/O con-
text suitable for concurrently processing nr_events opera-
tions. The ctx_idp argument must not point to an AIO con-
text that already exists, and must be initialized to 0 prior
to the call. On successful creation of the AIO context,
*ctx_idp is filled in with the resulting handle.
RETURN VALUE
On success, io_setup() returns 0. For the failure return,
see NOTES.
ERRORS
EAGAIN
The specified nr_events exceeds the limit of available
events, as defined in /proc/sys/fs/aio-max-nr (see
proc(5)).
EFAULT
An invalid pointer is passed for ctx_idp.
EINVAL
ctx_idp is not initialized, or the specified nr_events
exceeds internal limits. nr_events should be greater
than 0.
ENOMEM
Insufficient kernel resources are available.
ENOSYS
io_setup() is not implemented on this architecture.
VERSIONS
The asynchronous I/O system calls first appeared in Linux
2.5.
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IO_SETUP(2) (2020-12-21) IO_SETUP(2)
CONFORMING TO
io_setup() is Linux-specific and should not be used in pro-
grams that are intended to be portable.
NOTES
Glibc does not provide a wrapper function for this system
call. You could invoke it using syscall(2). But instead,
you probably want to use the io_setup() wrapper function
provided by libaio.
Note that the libaio wrapper function uses a different type
(io_context_t *) for the ctx_idp argument. Note also that
the libaio wrapper does not follow the usual C library con-
ventions for indicating errors: on error it returns a
negated error number (the negative of one of the values
listed in ERRORS). If the system call is invoked via
syscall(2), then the return value follows the usual conven-
tions for indicating an error: -1, with errno set to a (pos-
itive) value that indicates the error.
SEE ALSO
io_cancel(2), io_destroy(2), io_getevents(2), io_submit(2),
aio(7)
COLOPHON
This page is part of release 5.10 of the Linux man-pages
project. A description of the project, information about
reporting bugs, and the latest version of this page, can be
found at https://www.kernel.org/doc/man-pages/.
Page 2 Linux (printed 5/24/22)