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.\" Copyright (C) 2022 Jens Axboe <axboe@kernel.dk> .\" .\" SPDX-License-Identifier: LGPL-2.0-or-later .\" .TH io_uring_register_eventfd 3 "April 16, 2022" "liburing-2.2" "liburing Manual" .SH NAME io_uring_register_eventfd \- register an eventfd with a ring .SH SYNOPSIS .nf .B #include <liburing.h> .PP .BI "int io_uring_register_eventfd(struct io_uring *" ring "," .BI " int " fd ");" .PP .BI "int io_uring_register_eventfd_async(struct io_uring *" ring "," .BI " int " fd ");" .PP .BI "int io_uring_unregister_eventfd(struct io_uring *" ring ");" .fi .SH DESCRIPTION .PP .BR io_uring_register_eventfd (3) registers the eventfd file descriptor .I fd with the ring identified by .IR ring . Whenever completions are posted to the CQ ring, an eventfd notification is generated with the registered eventfd descriptor. If .BR 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, .BR 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. .SH 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. .SH RETURN VALUE Returns 0 on success, or or .BR -errno on error. .SH SEE ALSO .BR eventfd (2)
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13 entries across 13 versions & 1 rubygems