* [PATCH] io_uring: enable EPOLLEXCLUSIVE for accept poll
@ 2022-03-25 9:37 Dylan Yudaken
2022-03-25 12:32 ` Jens Axboe
0 siblings, 1 reply; 2+ messages in thread
From: Dylan Yudaken @ 2022-03-25 9:37 UTC (permalink / raw)
To: Jens Axboe, Pavel Begunkov, io-uring; +Cc: kernel-team, Dylan Yudaken
When polling sockets for accept, use EPOLLEXCLUSIVE. This is helpful
when multiple accept SQEs are submitted.
For O_NONBLOCK sockets multiple queued SQEs would previously have all
completed at once, but most with -EAGAIN as the result. Now only one
wakes up and completes.
For sockets without O_NONBLOCK there is no user facing change, but
internally the extra requests would previously be queued onto a worker
thread as they would wake up with no connection waiting, and be
punted. Now they do not wake up unnecessarily.
Co-developed-by: Jens Axboe <[email protected]>
Signed-off-by: Dylan Yudaken <[email protected]>
---
fs/io_uring.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 63299896555d..fced35d3ee85 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -968,6 +968,7 @@ struct io_op_def {
/* set if opcode supports polled "wait" */
unsigned pollin : 1;
unsigned pollout : 1;
+ unsigned poll_exclusive : 1;
/* op supports buffer selection */
unsigned buffer_select : 1;
/* do prep async if is going to be punted */
@@ -1062,6 +1063,7 @@ static const struct io_op_def io_op_defs[] = {
.needs_file = 1,
.unbound_nonreg_file = 1,
.pollin = 1,
+ .poll_exclusive = 1,
},
[IORING_OP_ASYNC_CANCEL] = {
.audit_skip = 1,
@@ -6280,7 +6282,8 @@ static int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags)
} else {
mask |= POLLOUT | POLLWRNORM;
}
-
+ if (def->poll_exclusive)
+ mask |= EPOLLEXCLUSIVE;
if (!(issue_flags & IO_URING_F_UNLOCKED) &&
!list_empty(&ctx->apoll_cache)) {
apoll = list_first_entry(&ctx->apoll_cache, struct async_poll,
base-commit: 6d4809f49bec8dc3b244debcb97f78239e52f5bb
--
2.30.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] io_uring: enable EPOLLEXCLUSIVE for accept poll
2022-03-25 9:37 [PATCH] io_uring: enable EPOLLEXCLUSIVE for accept poll Dylan Yudaken
@ 2022-03-25 12:32 ` Jens Axboe
0 siblings, 0 replies; 2+ messages in thread
From: Jens Axboe @ 2022-03-25 12:32 UTC (permalink / raw)
To: Pavel Begunkov, io-uring, Dylan Yudaken; +Cc: kernel-team
On Fri, 25 Mar 2022 02:37:55 -0700, Dylan Yudaken wrote:
> When polling sockets for accept, use EPOLLEXCLUSIVE. This is helpful
> when multiple accept SQEs are submitted.
>
> For O_NONBLOCK sockets multiple queued SQEs would previously have all
> completed at once, but most with -EAGAIN as the result. Now only one
> wakes up and completes.
>
> [...]
Applied, thanks!
[1/1] io_uring: enable EPOLLEXCLUSIVE for accept poll
commit: 52dd86406dfa322c8d42b3a4328858abdc6f1d85
Best regards,
--
Jens Axboe
^ permalink raw reply [flat|nested] 2+ messages in thread
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