io_setup(2)

1IO_SETUP(2)                Linux Programmer's Manual               IO_SETUP(2)
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NAME

6       io_setup - create an asynchronous I/O context
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SYNOPSIS

9       #include <linux/aio_abi.h>          /* Defines needed types */
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11       int io_setup(unsigned nr_events, io_context_t *ctx_idp);
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13       Note: There is no glibc wrapper for this system call; see NOTES.
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DESCRIPTION

16       The io_setup() system call creates an asynchronous I/O context suitable
17       for concurrently processing nr_events operations.  The ctx_idp argument
18       must  not point to an AIO context that already exists, and must be ini‐
19       tialized to 0 prior to the call.  On successful  creation  of  the  AIO
20       context, *ctx_idp is filled in with the resulting handle.
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RETURN VALUE

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

26       EAGAIN The  specified  nr_events exceeds the limit of available events,
27              as defined in /proc/sys/fs/aio-max-nr (see proc(5)).
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29       EFAULT An invalid pointer is passed for ctx_idp.
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31       EINVAL ctx_idp is not initialized, or the specified  nr_events  exceeds
32              internal limits.  nr_events should be greater than 0.
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34       ENOMEM Insufficient kernel resources are available.
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36       ENOSYS io_setup() is not implemented on this architecture.
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VERSIONS

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

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

46       Glibc does not provide a wrapper function for this  system  call.   You
47       could  invoke  it  using syscall(2).  But instead, you probably want to
48       use the io_setup() wrapper function provided by libaio.
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50       Note that the libaio wrapper function uses a  different  type  (io_con‐
51       text_t *)  for the ctx_idp argument.  Note also that the libaio wrapper
52       does not follow the usual C library conventions for indicating  errors:
53       on  error it returns a negated error number (the negative of one of the
54       values  listed  in  ERRORS).   If  the  system  call  is  invoked   via
55       syscall(2),  then  the  return  value follows the usual conventions for
56       indicating an error: -1, with errno set  to  a  (positive)  value  that
57       indicates the error.
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COLOPHON

63       This  page  is  part of release 5.07 of the Linux man-pages project.  A
64       description of the project, information about reporting bugs,  and  the
65       latest     version     of     this    page,    can    be    found    at
66       https://www.kernel.org/doc/man-pages/.
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70Linux                             2020-06-09                       IO_SETUP(2)