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| author | Jens Axboe <axboe@kernel.dk> | 2022-04-16 07:38:19 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2022-04-16 07:38:19 -0600 |
| commit | 8b205b8b82104589b869364bc11e1d9156be8dfa (patch) | |
| tree | c9bda4cb19fa4208f0e7b891374a123ec59ee794 | |
| parent | 7983bed070cbea274edc6224d7fb2137c82e3854 (diff) | |
| download | liburing-8b205b8b82104589b869364bc11e1d9156be8dfa.tar.gz liburing-8b205b8b82104589b869364bc11e1d9156be8dfa.tar.bz2 | |
man/io_uring_register.2: clarify eventfd notification counts
We may see both spurious eventfd notifications (eg an eventfd
notification was posted, yet no CQEs are available), as well as batched
notifications where a batch of CQEs are posted but only a single eventfd
notification generated.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | man/io_uring_register.2 | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/man/io_uring_register.2 b/man/io_uring_register.2 index cb63e6b..1e91caf 100644 --- a/man/io_uring_register.2 +++ b/man/io_uring_register.2 @@ -328,7 +328,13 @@ registered through this operation. .I arg must contain a pointer to the eventfd file descriptor, and .I nr_args -must be 1. Available since 5.2. +must be 1. Note that 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. Available since +5.2. An application can temporarily disable notifications, coming through the registered eventfd, by setting the |