Man page - io_uring_register_eventfd_async(3)

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Manual

io_uring_register_eventfd

NAME
SYNOPSIS
DESCRIPTION
NOTES
RETURN VALUE
SEE ALSO

NAME

io_uring_register_eventfd - register an eventfd with a ring

SYNOPSIS

#include <liburing.h>

int io_uring_register_eventfd(struct io_uring * ring ,
int fd );

int io_uring_register_eventfd_async(struct io_uring * ring ,
int fd );

int io_uring_unregister_eventfd(struct io_uring * ring );

DESCRIPTION

io_uring_register_eventfd (3) registers the eventfd file descriptor fd with the ring identified by ring .

Whenever completions are posted to the CQ ring, an eventfd notification is generated with the registered eventfd descriptor. If io_uring_register_eventfd_async (3) is used, only events that completed out-of-line will trigger a notification.

It notifications are no longer desired, io_uring_unregister_eventfd (3) may be called to remove the eventfd registration. No eventfd argument is needed, as a ring can only have a single eventfd registered.

NOTES

While io_uring generally takes care to avoid spurious events, they can occur. Similarly, batched completions of CQEs may only trigger a single eventfd notification even if multiple CQEs are posted. The application should make no assumptions on number of events being available having a direct correlation to eventfd notifications posted. An eventfd notification must thus only be treated as a hint to check the CQ ring for completions.

RETURN VALUE

Returns 0 on success, or -errno on error.

SEE ALSO

eventfd (2)