io_setup(2) — Linux manual page


IO_SETUP(2)               Linux Programmer's Manual              IO_SETUP(2)

NAME         top

       io_setup - create an asynchronous I/O context

SYNOPSIS         top

       #include <linux/aio_abi.h>          /* Defines needed types */

       int io_setup(unsigned nr_events, io_context_t *ctx_idp);

       Note: There is no glibc wrapper for this system call; see NOTES.

DESCRIPTION         top

       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.

RETURN VALUE         top

       On success, io_setup() returns 0.  For the failure return, see NOTES.

ERRORS         top

       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         top

       The asynchronous I/O system calls first appeared in Linux 2.5.

CONFORMING TO         top

       io_setup() is Linux-specific and should not be used in programs that
       are intended to be portable.

NOTES         top

       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.

SEE ALSO         top

       io_cancel(2), io_destroy(2), io_getevents(2), io_submit(2), aio(7)

COLOPHON         top

       This page is part of release 5.09 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

Linux                            2020-06-09                      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(5)procfs(5)systemd.exec(5)aio(7)