io_setup(2) System Calls Manual io_setup(2)
NAME
io_setup - create an asynchronous I/O context
LIBRARY
Standard C library (libc, -lc)
Alternatively, Asynchronous I/O library (libaio, -laio); see NOTES.
SYNOPSIS
#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 NOTES.
DESCRIPTION
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 NOTES.
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 ini-
tialized 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.
STANDARDS
io_setup() is Linux-specific and should not be used in programs that
are intended to be portable.
NOTES
glibc does not provide a wrapper for this system call. You could in-
voke 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_con-
text_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 in-
dicating an error: -1, with errno set to a (positive) value that indi-
cates the error.
SEE ALSO
io_cancel(2), io_destroy(2), io_getevents(2), io_submit(2), aio(7)
Linux man-pages 6.03 2023-02-05 io_setup(2)
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