Manpage of IO_SETUP
IO_SETUPSection: Linux Programmer's Manual (2)
NAMEio_setup - create an asynchronous I/O context
#include <linux/aio_abi.h> /* Defines needed types */ int io_setup(unsigned nr_events, aio_context_t *ctx_idp);
The io_setup() system call creates an asynchronous I/O context suitable for concurrently processing nr_events operations. The ctx_idpargument 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 VALUEOn success, io_setup() returns 0. For the failure return, see NOTES.
- The specified nr_events exceeds the user's limit of available events, as defined in /proc/sys/fs/aio-max-nr.
- An invalid pointer is passed for ctx_idp.
- ctx_idp is not initialized, or the specified nr_eventsexceeds internal limits. nr_events should be greater than 0.
- Insufficient kernel resources are available.
- io_setup() is not implemented on this architecture.
NOTESGlibc does not provide a wrapper function 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 libaiowrapper function uses a different type (io_context_t *) for the ctx_idpargument. Note also that the libaiowrapper 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 errnoset to a (positive) value that indicates the error.
SEE ALSOio_cancel(2), io_destroy(2), io_getevents(2), io_submit(2), aio(7)
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