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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | STANDARDS | HISTORY | SEE ALSO | COLOPHON |
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io_setup(2) System Calls Manual io_setup(2)
io_setup - create an asynchronous I/O context
Standard C library (libc, -lc)
Alternatively, Asynchronous I/O library (libaio, -laio); see
VERSIONS.
#include <linux/aio_abi.h> /* Defines needed types */
long io_setup(unsigned int nr_events, aio_context_t *ctx_idp);
Note: There is no glibc wrapper for this system call; see
VERSIONS.
Note: this page describes the raw Linux system call interface.
The wrapper function provided by libaio uses a different type for
the ctx_idp argument. See VERSIONS.
The io_setup() system call creates an asynchronous I/O context
suitable for concurrently processing nr_events operations. The
ctx_idp argument must not point to an AIO context 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.
On success, io_setup() returns 0. For the failure return, see
VERSIONS.
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.
glibc does not provide a wrapper 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 conventions 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 conventions for indicating an error: -1, with errno set to a
(positive) value that indicates the error.
Linux.
Linux 2.5.
io_cancel(2), io_destroy(2), io_getevents(2), io_submit(2), aio(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-05-17 io_setup(2)
Pages that refer to this page: fork(2), io_cancel(2), io_destroy(2), io_getevents(2), io_submit(2), syscalls(2), proc_sys_fs(5), systemd.exec(5), aio(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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