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From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Subject: [PATCH 13/13] io_uring: don't bounce submit_state cachelines
Date: Sun, 16 May 2021 22:58:12 +0100	[thread overview]
Message-ID: <290cb5412b76892e8631978ee8ab9db0c6290dd5.1621201931.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>

struct io_submit_state contains struct io_comp_state and so
locked_free_*, that renders cachelines around ->locked_free* being
invalidated on most non-inline completions, that may terrorise caches if
submissions and completions are done by different tasks.

Signed-off-by: Pavel Begunkov <[email protected]>
---
 fs/io_uring.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index a0b3a9c99044..e387ce687f4d 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -298,11 +298,8 @@ struct io_sq_data {
 struct io_comp_state {
 	struct io_kiocb		*reqs[IO_COMPL_BATCH];
 	unsigned int		nr;
-	unsigned int		locked_free_nr;
 	/* inline/task_work completion list, under ->uring_lock */
 	struct list_head	free_list;
-	/* IRQ completion list, under ->completion_lock */
-	struct list_head	locked_free_list;
 };
 
 struct io_submit_link {
@@ -379,6 +376,9 @@ struct io_ring_ctx {
 	} ____cacheline_aligned_in_smp;
 
 	struct io_submit_state		submit_state;
+	/* IRQ completion list, under ->completion_lock */
+	struct list_head	locked_free_list;
+	unsigned int		locked_free_nr;
 
 	struct io_rings	*rings;
 
@@ -1184,7 +1184,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	init_llist_head(&ctx->rsrc_put_llist);
 	INIT_LIST_HEAD(&ctx->tctx_list);
 	INIT_LIST_HEAD(&ctx->submit_state.comp.free_list);
-	INIT_LIST_HEAD(&ctx->submit_state.comp.locked_free_list);
+	INIT_LIST_HEAD(&ctx->locked_free_list);
 	return ctx;
 err:
 	kfree(ctx->dummy_ubuf);
@@ -1587,8 +1587,6 @@ static void io_req_complete_post(struct io_kiocb *req, long res,
 	 * free_list cache.
 	 */
 	if (req_ref_put_and_test(req)) {
-		struct io_comp_state *cs = &ctx->submit_state.comp;
-
 		if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK)) {
 			if (req->flags & (REQ_F_LINK_TIMEOUT | REQ_F_FAIL))
 				io_disarm_next(req);
@@ -1599,8 +1597,8 @@ static void io_req_complete_post(struct io_kiocb *req, long res,
 		}
 		io_dismantle_req(req);
 		io_put_task(req->task, 1);
-		list_add(&req->compl.list, &cs->locked_free_list);
-		cs->locked_free_nr++;
+		list_add(&req->compl.list, &ctx->locked_free_list);
+		ctx->locked_free_nr++;
 	} else {
 		if (!percpu_ref_tryget(&ctx->refs))
 			req = NULL;
@@ -1655,8 +1653,8 @@ static void io_flush_cached_locked_reqs(struct io_ring_ctx *ctx,
 					struct io_comp_state *cs)
 {
 	spin_lock_irq(&ctx->completion_lock);
-	list_splice_init(&cs->locked_free_list, &cs->free_list);
-	cs->locked_free_nr = 0;
+	list_splice_init(&ctx->locked_free_list, &cs->free_list);
+	ctx->locked_free_nr = 0;
 	spin_unlock_irq(&ctx->completion_lock);
 }
 
@@ -1672,7 +1670,7 @@ static bool io_flush_cached_reqs(struct io_ring_ctx *ctx)
 	 * locked cache, grab the lock and move them over to our submission
 	 * side cache.
 	 */
-	if (READ_ONCE(cs->locked_free_nr) > IO_COMPL_BATCH)
+	if (READ_ONCE(ctx->locked_free_nr) > IO_COMPL_BATCH)
 		io_flush_cached_locked_reqs(ctx, cs);
 
 	nr = state->free_reqs;
-- 
2.31.1


  parent reply	other threads:[~2021-05-16 21:58 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-16 21:57 [PATCH for-next 00/13] 5.14 cleanups Pavel Begunkov
2021-05-16 21:58 ` [PATCH 01/13] io_uring: improve sqpoll event/state handling Pavel Begunkov
2021-05-16 21:58 ` [PATCH 02/13] io_uring: improve sq_thread waiting check Pavel Begunkov
2021-05-16 21:58 ` [PATCH 03/13] io_uring: remove unused park_task_work Pavel Begunkov
2021-05-16 21:58 ` [PATCH 04/13] io_uring: simplify waking sqo_sq_wait Pavel Begunkov
2021-05-16 21:58 ` [PATCH 05/13] io_uring: get rid of files in exit cancel Pavel Begunkov
2021-05-16 21:58 ` [PATCH 06/13] io_uring: make fail flag not link specific Pavel Begunkov
2021-05-16 21:58 ` [PATCH 07/13] io_uring: shuffle rarely used ctx fields Pavel Begunkov
2021-05-16 21:58 ` [PATCH 08/13] io_uring: better locality for rsrc fields Pavel Begunkov
2021-05-16 21:58 ` [PATCH 09/13] io_uring: remove dependency on ring->sq/cq_entries Pavel Begunkov
2021-05-16 21:58 ` [PATCH 10/13] io_uring: deduce cq_mask from cq_entries Pavel Begunkov
2021-05-16 21:58 ` [PATCH 11/13] io_uring: kill cached_cq_overflow Pavel Begunkov
2021-05-16 21:58 ` [PATCH 12/13] io_uring: rename io_get_cqring Pavel Begunkov
2021-05-16 21:58 ` Pavel Begunkov [this message]
2021-05-24 17:41 ` [PATCH for-next 00/13] 5.14 cleanups Jens Axboe

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