io_setup(2) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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 */

       long io_setup(unsigned nr_events, aio_context_t *ctx_idp);

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

DESCRIPTION         top

       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.

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 5.10 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
       https://www.kernel.org/doc/man-pages/.

Linux                          2020-12-21                    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)systemd.exec(5)aio(7)