[for-next] io_uring: static_key for !IORING_SETUP_NO_SQARRAY

Commit Message

Pavel Begunkov Oct. 18, 2024, 4:07 p.m. UTC

IORING_SETUP_NO_SQARRAY should be preferred and used by default by
liburing, optimise flag checking in io_get_sqe() with a static key.

Signed-off-by: Pavel Begunkov <[e-mail]>
---
 io_uring/io_uring.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

Comments

Jens Axboe Oct. 18, 2024, 6:37 p.m. UTC | #1

On Fri, 18 Oct 2024 17:07:59 +0100, Pavel Begunkov wrote:
> IORING_SETUP_NO_SQARRAY should be preferred and used by default by
> liburing, optimise flag checking in io_get_sqe() with a static key.
> 
> 

Applied, thanks!

[1/1] io_uring: static_key for !IORING_SETUP_NO_SQARRAY
      commit: 9812732ce65b9690720f772c07afadf38dd7d8ef

Best regards,

Patch

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index ed34f356d703..e253f0176d0a 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -70,6 +70,7 @@ 
 #include <linux/io_uring/cmd.h>
 #include <linux/audit.h>
 #include <linux/security.h>
+#include <linux/jump_label.h>
 #include <asm/shmparam.h>
 
 #define CREATE_TRACE_POINTS
@@ -149,6 +150,8 @@  static bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
 
 static void io_queue_sqe(struct io_kiocb *req);
 
+static __read_mostly DEFINE_STATIC_KEY_FALSE(io_key_has_sqarray);
+
 struct kmem_cache *req_cachep;
 static struct workqueue_struct *iou_wq __ro_after_init;
 
@@ -2249,7 +2252,8 @@  static bool io_get_sqe(struct io_ring_ctx *ctx, const struct io_uring_sqe **sqe)
 	unsigned mask = ctx->sq_entries - 1;
 	unsigned head = ctx->cached_sq_head++ & mask;
 
-	if (!(ctx->flags & IORING_SETUP_NO_SQARRAY)) {
+	if (static_branch_unlikely(&io_key_has_sqarray) &&
+	    (!(ctx->flags & IORING_SETUP_NO_SQARRAY))) {
 		head = READ_ONCE(ctx->sq_array[head]);
 		if (unlikely(head >= ctx->sq_entries)) {
 			/* drop invalid entries */
@@ -2753,6 +2757,9 @@  static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
 	}
 	io_rings_free(ctx);
 
+	if (!(ctx->flags & IORING_SETUP_NO_SQARRAY))
+		static_branch_dec(&io_key_has_sqarray);
+
 	percpu_ref_exit(&ctx->refs);
 	free_uid(ctx->user);
 	io_req_caches_free(ctx);
@@ -3545,6 +3552,9 @@  static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
 	ctx->clockid = CLOCK_MONOTONIC;
 	ctx->clock_offset = 0;
 
+	if (!(ctx->flags & IORING_SETUP_NO_SQARRAY))
+		static_branch_inc(&io_key_has_sqarray);
+
 	if ((ctx->flags & IORING_SETUP_DEFER_TASKRUN) &&
 	    !(ctx->flags & IORING_SETUP_IOPOLL) &&
 	    !(ctx->flags & IORING_SETUP_SQPOLL))