NAME

       io_setup - create an asynchronous I/O context

LIBRARY

       Standard C library (libc, -lc)

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

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 VERSIONS.

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 VERSIONS.

       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 VERSIONS.

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

       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.

STANDARDS

       Linux.

HISTORY

       Linux 2.5.

SEE ALSO

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