From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>, io-uring@vger.kernel.org
Subject: [PATCH 04/12] io_uring: refactor io_get_sqe()
Date: Mon, 14 Jun 2021 23:37:23 +0100 [thread overview]
Message-ID: <866ad6e4ef4851c7c61f6b0e08dbd0a8d1abce84.1623709150.git.asml.silence@gmail.com> (raw)
In-Reply-To: <cover.1623709150.git.asml.silence@gmail.com>
The line of io_get_sqe() evaluating @head consists of too many
operations including READ_ONCE(), it's not convenient for probing.
Refactor it also improving readability.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5cc0c4dd2709..3baacfe2c9b7 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6685,8 +6685,8 @@ static void io_commit_sqring(struct io_ring_ctx *ctx)
*/
static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx)
{
- u32 *sq_array = ctx->sq_array;
unsigned head, mask = ctx->sq_entries - 1;
+ unsigned sq_idx = ctx->cached_sq_head++ & mask;
/*
* The cached sq head (or cq tail) serves two purposes:
@@ -6696,7 +6696,7 @@ static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx)
* 2) allows the kernel side to track the head on its own, even
* though the application is the one updating it.
*/
- head = READ_ONCE(sq_array[ctx->cached_sq_head++ & mask]);
+ head = READ_ONCE(ctx->sq_array[sq_idx]);
if (likely(head < ctx->sq_entries))
return &ctx->sq_sqes[head];
--
2.31.1
next prev parent reply other threads:[~2021-06-14 22:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-14 22:37 [PATCH 5.14 00/12] for-next optimisations Pavel Begunkov
2021-06-14 22:37 ` [PATCH 01/12] io_uring: keep SQ pointers in a single cacheline Pavel Begunkov
2021-06-14 22:37 ` [PATCH 02/12] io_uring: move ctx->flags from SQ cacheline Pavel Begunkov
2021-06-14 22:37 ` [PATCH 03/12] io_uring: shuffle more fields into SQ ctx section Pavel Begunkov
2021-06-14 22:37 ` Pavel Begunkov [this message]
2021-06-14 22:37 ` [PATCH 05/12] io_uring: don't cache number of dropped SQEs Pavel Begunkov
2021-06-14 22:37 ` [PATCH 06/12] io_uring: optimise completion timeout flushing Pavel Begunkov
2021-06-14 22:37 ` [PATCH 07/12] io_uring: small io_submit_sqe() optimisation Pavel Begunkov
2021-06-14 22:37 ` [PATCH 08/12] io_uring: clean up check_overflow flag Pavel Begunkov
2021-06-14 22:37 ` [PATCH 09/12] io_uring: wait heads renaming Pavel Begunkov
2021-06-14 22:37 ` [PATCH 10/12] io_uring: move uring_lock location Pavel Begunkov
2021-06-14 22:37 ` [PATCH 11/12] io_uring: refactor io_req_defer() Pavel Begunkov
2021-06-14 22:37 ` [PATCH 12/12] io_uring: optimise non-drain path Pavel Begunkov
2021-06-15 12:27 ` [PATCH 5.14 00/12] for-next optimisations Pavel Begunkov
2021-06-15 21:38 ` Jens Axboe
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