2020-01-17 03:53:28

by Pavel Begunkov

Subject: [PATCH] io_uring: remove extra check in __io_commit_cqring

__io_commit_cqring() is almost always called when there is a change in
the rings, so the check is rather pessimising.

Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index f9709a3a673c..ea91f4d92fc0 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -859,14 +859,12 @@ static void __io_commit_cqring(struct io_ring_ctx *ctx)
{
struct io_rings *rings = ctx->rings;

- if (ctx->cached_cq_tail != READ_ONCE(rings->cq.tail)) {
- /* order cqe stores with ring update */
- smp_store_release(&rings->cq.tail, ctx->cached_cq_tail);
+ /* order cqe stores with ring update */
+ smp_store_release(&rings->cq.tail, ctx->cached_cq_tail);

- if (wq_has_sleeper(&ctx->cq_wait)) {
- wake_up_interruptible(&ctx->cq_wait);
- kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
- }
+ if (wq_has_sleeper(&ctx->cq_wait)) {
+ wake_up_interruptible(&ctx->cq_wait);
+ kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
}
}

--
2.24.0

2020-01-17 04:02:30

by Jens Axboe

Subject: Re: [PATCH] io_uring: remove extra check in __io_commit_cqring

On 1/16/20 5:52 PM, Pavel Begunkov wrote:
> __io_commit_cqring() is almost always called when there is a change in
> the rings, so the check is rather pessimising.

Applied, thanks.

--
Jens Axboe