io_getevents(2)               System Calls Manual              io_getevents(2)

NAME
       io_getevents - read asynchronous I/O events from the completion queue

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <linux/aio_abi.h>    /* Definition of *io_* types */
       #include <sys/syscall.h>      /* Definition of SYS_* constants */
       #include <unistd.h>

       int syscall(SYS_io_getevents, aio_context_t ctx_id,
                   long min_nr, long nr, struct io_event *events,
                   struct timespec *timeout);

DESCRIPTION
       Note: you probably want to use the io_getevents(3) wrapper function
       provided by libaio; see VERSIONS.

       The io_getevents() system call attempts to read at least min_nr events
       and up to nr events from the completion queue of the AIO context
       specified by ctx_id.

       The timeout argument specifies the amount of time to wait for events,
       and is specified as a relative timeout in a timespec(3) structure.

       The specified time will be rounded up to the system clock granularity
       and is guaranteed not to expire early.

       Specifying timeout as NULL means block indefinitely until at least
       min_nr events have been obtained.

RETURN VALUE
       On success, io_getevents() returns the number of events read.  This may
       be 0, or a value less than min_nr, if the timeout expired.  It may also
       be a nonzero value less than min_nr, if the call was interrupted by a
       signal handler.

       On error, -1 is returned, and errno is set to indicate the error.

ERRORS
       EFAULT Either events or timeout is an invalid pointer.

       EINTR  Interrupted by a signal handler; see signal(7).

       EINVAL ctx_id is invalid.

       EINVAL min_nr is out of range or nr is out of range.

       ENOSYS io_getevents() is not implemented on this architecture.

VERSIONS
       libaio <https://pagure.io/libaio> provides a wrapper function with the
       same name, but different prototype and return value.  You probably want
       to use that wrapper.

STANDARDS
       Linux.

HISTORY
       Linux 2.5.

SEE ALSO
       io_cancel(2), io_destroy(2), io_setup(2), io_submit(2),
       io_getevents(3), timespec(3), aio(7), time(7)

Linux man-pages 6.19              2026-04-11                   io_getevents(2)