NAME

       io_setup - create an asynchronous I/O context

LIBRARY

       Standard C library (libc, -lc)

       Alternatively, Asynchronous I/O library (libaio, -laio); see NOTES.

SYNOPSIS

       #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.

DESCRIPTION

       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

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

ERRORS

       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

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

STANDARDS

       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  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)