io_setup - create an asynchronous I/O context
#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.
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.
The specified nr_events
exceeds the limit of available
events, as defined in /proc/sys/fs/aio-max-nr
(see
proc(5)).
An invalid pointer is passed for ctx_idp
.
ctx_idp
is not initialized, or the specified
nr_events
exceeds internal limits. nr_events
should be
greater than 0.
Insufficient kernel resources are available.
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 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
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)
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