linux-kernel - [PATCH 01/23] io_uring: shuffle rarely used ctx fields

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Message-Id: <485abb65cf032f4ddf13dcc0bd60e5475638efc2.1621424513.git.asml.silence@gmail.com>
Date:   Wed, 19 May 2021 15:13:12 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     io-uring@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Jens Axboe <axboe@...nel.dk>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Horst Schirmeier <horst.schirmeier@...dortmund.de>,
        "Franz-B . Tuneke" <franz-bernhard.tuneke@...dortmund.de>,
        Christian Dietrich <stettberger@...ucode.de>
Subject: [PATCH 01/23] io_uring: shuffle rarely used ctx fields

There is a bunch of scattered around ctx fields that are almost never
used, e.g. only on ring exit, plunge them to the end, better locality,
better aesthetically.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 fs/io_uring.c | 36 +++++++++++++++++-------------------
 1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 9ac5e278a91e..7e3410ce100a 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -367,9 +367,6 @@ struct io_ring_ctx {
 		unsigned		cached_cq_overflow;
 		unsigned long		sq_check_overflow;
 
-		/* hashed buffered write serialization */
-		struct io_wq_hash	*hash_map;
-
 		struct list_head	defer_list;
 		struct list_head	timeout_list;
 		struct list_head	cq_overflow_list;
@@ -386,9 +383,6 @@ struct io_ring_ctx {
 
 	struct io_rings	*rings;
 
-	/* Only used for accounting purposes */
-	struct mm_struct	*mm_account;
-
 	const struct cred	*sq_creds;	/* cred used for __io_sq_thread() */
 	struct io_sq_data	*sq_data;	/* if using sq thread polling */
 
@@ -409,14 +403,6 @@ struct io_ring_ctx {
 	unsigned		nr_user_bufs;
 	struct io_mapped_ubuf	**user_bufs;
 
-	struct user_struct	*user;
-
-	struct completion	ref_comp;
-
-#if defined(CONFIG_UNIX)
-	struct socket		*ring_sock;
-#endif
-
 	struct xarray		io_buffers;
 
 	struct xarray		personalities;
@@ -460,12 +446,24 @@ struct io_ring_ctx {
 
 	struct io_restriction		restrictions;
 
-	/* exit task_work */
-	struct callback_head		*exit_task_work;
-
 	/* Keep this last, we don't need it for the fast path */
-	struct work_struct		exit_work;
-	struct list_head		tctx_list;
+	struct {
+		#if defined(CONFIG_UNIX)
+			struct socket		*ring_sock;
+		#endif
+		/* hashed buffered write serialization */
+		struct io_wq_hash		*hash_map;
+
+		/* Only used for accounting purposes */
+		struct user_struct		*user;
+		struct mm_struct		*mm_account;
+
+		/* ctx exit and cancelation */
+		struct callback_head		*exit_task_work;
+		struct work_struct		exit_work;
+		struct list_head		tctx_list;
+		struct completion		ref_comp;
+	};
 };
 
 struct io_uring_task {
-- 
2.31.1