io_setup

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



NAME
       io_setup - create an asynchronous I/O context

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

       int io_setup(unsigned nr_events, aio_context_t *ctx_idp);

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

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

ERRORS
       EAGAIN The specified nr_events exceeds the user's limit of available
              events, as defined in /proc/sys/fs/aio-max-nr.

       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.

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

COLOPHON
       This page is part of release 5.03 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                             2017-09-15                       IO_SETUP(2)