io_setup(2) — Linux manual page

io_setup(2)                System Calls Manual               io_setup(2)

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)

COLOPHON

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       man-pages@man7.org

Linux man-pages 6.9.1          2024-05-02                    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_sys_fs(5), systemd.exec(5), aio(7)

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