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Diffstat (limited to 'man/io_uring_register_eventfd.3')
| -rw-r--r-- | man/io_uring_register_eventfd.3 | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/man/io_uring_register_eventfd.3 b/man/io_uring_register_eventfd.3 new file mode 100644 index 0000000..5cbe72a --- /dev/null +++ b/man/io_uring_register_eventfd.3 @@ -0,0 +1,51 @@ +.\" 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) |