io_setup - create an asynchronous I/O context
Standard C library (
libc,
-lc)
Alternatively, Asynchronous I/O library (
libaio,
-laio); see
NOTES.
#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.
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
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 NOTES.
- 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.
The asynchronous I/O system calls first appeared in Linux 2.5.
io_setup() is Linux-specific and should not be used in programs that are
intended to be portable.
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.
io_cancel(2),
io_destroy(2),
io_getevents(2),
io_submit(2),
aio(7)