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* [PATCH] io_uring: remove extra check in __io_commit_cqring
@ 2020-01-17  0:52 Pavel Begunkov
  2020-01-17  2:59 ` Jens Axboe
  0 siblings, 1 reply; 2+ messages in thread
From: Pavel Begunkov @ 2020-01-17  0:52 UTC (permalink / raw)
  To: Jens Axboe, io-uring, linux-kernel

__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


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] io_uring: remove extra check in __io_commit_cqring
  2020-01-17  0:52 [PATCH] io_uring: remove extra check in __io_commit_cqring Pavel Begunkov
@ 2020-01-17  2:59 ` Jens Axboe
  0 siblings, 0 replies; 2+ messages in thread
From: Jens Axboe @ 2020-01-17  2:59 UTC (permalink / raw)
  To: Pavel Begunkov, io-uring, linux-kernel

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


^ permalink raw reply	[flat|nested] 2+ messages in thread

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