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authorJens Axboe <axboe@kernel.dk>2020-12-18 12:34:38 -0700
committerJens Axboe <axboe@kernel.dk>2020-12-18 12:34:38 -0700
commitb09d1d45c390c6567c1d6ac1e1615cff4e11f274 (patch)
tree68a86362b5f60e66fb75e8c4879f7ece6b19e4a6
parent88b845dee001723c4a0db1fe5477de735b6d3bb0 (diff)
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man/io_uring_enter.2: ensure all IORING_ENTER_* flags are documented
Fixes: https://github.com/axboe/liburing/issues/271 Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--man/io_uring_enter.234
1 files changed, 27 insertions, 7 deletions
diff --git a/man/io_uring_enter.2 b/man/io_uring_enter.2
index a1e486a..dd33c38 100644
--- a/man/io_uring_enter.2
+++ b/man/io_uring_enter.2
@@ -29,15 +29,35 @@ initiated by this call or previous calls to
is the file descriptor returned by
.BR io_uring_setup (2).
.I to_submit
-specifies the number of I/Os to submit from the submission queue. If
-the
+specifies the number of I/Os to submit from the submission queue.
+.I flags
+is a bitmask of the following values:
+.TP
.B IORING_ENTER_GETEVENTS
-bit is set in
-.IR flags ,
-then the system call will attempt to wait for
+If this flag is set, then the system call will wait for the specificied
+number of events in
.I min_complete
-event completions before returning. If the io_uring instance was
-configured for polling, by specifying
+before returning. This flag can be set along with
+.I to_submit
+to both submit and complete events in a single system call.
+.TP
+.B IORING_ENTER_SQ_WAKEUP
+If the ring has been created with
+.B IORING_SETUP_SQPOLL,
+then this flag asks the kernel to wakeup the SQ kernel thread to submit IO.
+.TP
+.B IORING_ENTER_SQ_WAIT
+If the ring has been created with
+.B IORING_SETUP_SQPOLL,
+then the application has no real insight into when the SQ kernel thread has
+consumed entries from the SQ ring. This can lead to a situation where the
+application can no longer get a free SQE entry to submit, without knowing
+when it one becomes available as the SQ kernel thread consumes them. If
+the system call is used with this flag set, then it will wait until at least
+one entry is free in the SQ ring.
+.PP
+.PP
+If the io_uring instance was configured for polling, by specifying
.B IORING_SETUP_IOPOLL
in the call to
.BR io_uring_setup (2),