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From: Pavel Begunkov <[email protected]>
To: [email protected], [email protected],
	[email protected]
Cc: "David S . Miller" <[email protected]>,
	Jakub Kicinski <[email protected]>,
	Jonathan Lemon <[email protected]>,
	Willem de Bruijn <[email protected]>,
	Jens Axboe <[email protected]>, David Ahern <[email protected]>,
	[email protected], Pavel Begunkov <[email protected]>
Subject: [PATCH net-next v4 15/27] io_uring: cache struct io_notif
Date: Thu,  7 Jul 2022 12:49:46 +0100	[thread overview]
Message-ID: <b033c7240e294a543f8ddd20d39dd272ac771a55.1657194434.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>

kmalloc'ing struct io_notif is too expensive when done frequently, cache
them as many other resources in io_uring. Keep two list, the first one
is from where we're getting notifiers, it's protected by ->uring_lock.
The second is protected by ->completion_lock, to which we queue released
notifiers. Then we splice one list into another when needed.

Signed-off-by: Pavel Begunkov <[email protected]>
---
 include/linux/io_uring_types.h |  7 +++++
 io_uring/io_uring.c            |  3 ++
 io_uring/notif.c               | 57 +++++++++++++++++++++++++++++-----
 io_uring/notif.h               |  5 +++
 4 files changed, 65 insertions(+), 7 deletions(-)

diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 95334e678586..66ab009e7a6b 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -244,6 +244,9 @@ struct io_ring_ctx {
 		struct xarray		io_bl_xa;
 		struct list_head	io_buffers_cache;
 
+		/* struct io_notif cache, protected by uring_lock */
+		struct list_head	notif_list;
+
 		struct io_hash_table	cancel_table_locked;
 		struct list_head	cq_overflow_list;
 		struct list_head	apoll_cache;
@@ -255,6 +258,10 @@ struct io_ring_ctx {
 	struct io_wq_work_list	locked_free_list;
 	unsigned int		locked_free_nr;
 
+	/* struct io_notif cache protected by completion_lock */
+	struct list_head	notif_list_locked;
+	unsigned int		notif_locked_nr;
+
 	const struct cred	*sq_creds;	/* cred used for __io_sq_thread() */
 	struct io_sq_data	*sq_data;	/* if using sq thread polling */
 
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index ad816afe2345..bdc5a2839d94 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -318,6 +318,8 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	INIT_WQ_LIST(&ctx->locked_free_list);
 	INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func);
 	INIT_WQ_LIST(&ctx->submit_state.compl_reqs);
+	INIT_LIST_HEAD(&ctx->notif_list);
+	INIT_LIST_HEAD(&ctx->notif_list_locked);
 	return ctx;
 err:
 	kfree(ctx->dummy_ubuf);
@@ -2498,6 +2500,7 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
 	WARN_ON_ONCE(!list_empty(&ctx->ltimeout_list));
 	WARN_ON_ONCE(ctx->notif_slots || ctx->nr_notif_slots);
 
+	io_notif_cache_purge(ctx);
 	io_mem_free(ctx->rings);
 	io_mem_free(ctx->sq_sqes);
 
diff --git a/io_uring/notif.c b/io_uring/notif.c
index 6ee948af6a49..b257db2120b4 100644
--- a/io_uring/notif.c
+++ b/io_uring/notif.c
@@ -15,10 +15,12 @@ static void __io_notif_complete_tw(struct callback_head *cb)
 
 	io_cq_lock(ctx);
 	io_fill_cqe_aux(ctx, notif->tag, 0, notif->seq, true);
+
+	list_add(&notif->cache_node, &ctx->notif_list_locked);
+	ctx->notif_locked_nr++;
 	io_cq_unlock_post(ctx);
 
 	percpu_ref_put(&ctx->refs);
-	kfree(notif);
 }
 
 static inline void io_notif_complete(struct io_notif *notif)
@@ -45,21 +47,62 @@ static void io_uring_tx_zerocopy_callback(struct sk_buff *skb,
 	queue_work(system_unbound_wq, &notif->commit_work);
 }
 
+static void io_notif_splice_cached(struct io_ring_ctx *ctx)
+	__must_hold(&ctx->uring_lock)
+{
+	spin_lock(&ctx->completion_lock);
+	list_splice_init(&ctx->notif_list_locked, &ctx->notif_list);
+	ctx->notif_locked_nr = 0;
+	spin_unlock(&ctx->completion_lock);
+}
+
+void io_notif_cache_purge(struct io_ring_ctx *ctx)
+	__must_hold(&ctx->uring_lock)
+{
+	io_notif_splice_cached(ctx);
+
+	while (!list_empty(&ctx->notif_list)) {
+		struct io_notif *notif = list_first_entry(&ctx->notif_list,
+						struct io_notif, cache_node);
+
+		list_del(&notif->cache_node);
+		kfree(notif);
+	}
+}
+
+static inline bool io_notif_has_cached(struct io_ring_ctx *ctx)
+	__must_hold(&ctx->uring_lock)
+{
+	if (likely(!list_empty(&ctx->notif_list)))
+		return true;
+	if (data_race(READ_ONCE(ctx->notif_locked_nr) <= IO_NOTIF_SPLICE_BATCH))
+		return false;
+	io_notif_splice_cached(ctx);
+	return !list_empty(&ctx->notif_list);
+}
+
 struct io_notif *io_alloc_notif(struct io_ring_ctx *ctx,
 				struct io_notif_slot *slot)
 	__must_hold(&ctx->uring_lock)
 {
 	struct io_notif *notif;
 
-	notif = kzalloc(sizeof(*notif), GFP_ATOMIC | __GFP_ACCOUNT);
-	if (!notif)
-		return NULL;
+	if (likely(io_notif_has_cached(ctx))) {
+		notif = list_first_entry(&ctx->notif_list,
+					 struct io_notif, cache_node);
+		list_del(&notif->cache_node);
+	} else {
+		notif = kzalloc(sizeof(*notif), GFP_ATOMIC | __GFP_ACCOUNT);
+		if (!notif)
+			return NULL;
+		/* pre-initialise some fields */
+		notif->ctx = ctx;
+		notif->uarg.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
+		notif->uarg.callback = io_uring_tx_zerocopy_callback;
+	}
 
 	notif->seq = slot->seq++;
 	notif->tag = slot->tag;
-	notif->ctx = ctx;
-	notif->uarg.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
-	notif->uarg.callback = io_uring_tx_zerocopy_callback;
 	/* master ref owned by io_notif_slot, will be dropped on flush */
 	refcount_set(&notif->uarg.refcnt, 1);
 	percpu_ref_get(&ctx->refs);
diff --git a/io_uring/notif.h b/io_uring/notif.h
index 3d7a1d242e17..b23c9c0515bb 100644
--- a/io_uring/notif.h
+++ b/io_uring/notif.h
@@ -5,6 +5,8 @@
 #include <net/sock.h>
 #include <linux/nospec.h>
 
+#define IO_NOTIF_SPLICE_BATCH	32
+
 struct io_notif {
 	struct ubuf_info	uarg;
 	struct io_ring_ctx	*ctx;
@@ -13,6 +15,8 @@ struct io_notif {
 	u64			tag;
 	/* see struct io_notif_slot::seq */
 	u32			seq;
+	/* hook into ctx->notif_list and ctx->notif_list_locked */
+	struct list_head	cache_node;
 
 	union {
 		struct callback_head	task_work;
@@ -41,6 +45,7 @@ struct io_notif_slot {
 };
 
 int io_notif_unregister(struct io_ring_ctx *ctx);
+void io_notif_cache_purge(struct io_ring_ctx *ctx);
 
 struct io_notif *io_alloc_notif(struct io_ring_ctx *ctx,
 				struct io_notif_slot *slot);
-- 
2.36.1



  parent reply	other threads:[~2022-07-07 11:52 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-07 11:49 [PATCH net-next v4 00/27] io_uring zerocopy send Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 01/27] ipv4: avoid partial copy for zc Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 02/27] ipv6: " Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 03/27] skbuff: don't mix ubuf_info from different sources Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 04/27] skbuff: add SKBFL_DONT_ORPHAN flag Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 05/27] skbuff: carry external ubuf_info in msghdr Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 06/27] net: Allow custom iter handler " Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 07/27] net: introduce managed frags infrastructure Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 08/27] net: introduce __skb_fill_page_desc_noacc Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 09/27] ipv4/udp: support externally provided ubufs Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 10/27] ipv6/udp: " Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 11/27] tcp: " Pavel Begunkov
2022-07-08  4:06   ` David Ahern
2022-07-07 11:49 ` [PATCH net-next v4 12/27] io_uring: initialise msghdr::msg_ubuf Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 13/27] io_uring: export io_put_task() Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 14/27] io_uring: add zc notification infrastructure Pavel Begunkov
2022-07-07 11:49 ` Pavel Begunkov [this message]
2022-07-07 11:49 ` [PATCH net-next v4 16/27] io_uring: complete notifiers in tw Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 17/27] io_uring: add rsrc referencing for notifiers Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 18/27] io_uring: add notification slot registration Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 19/27] io_uring: wire send zc request type Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 20/27] io_uring: account locked pages for non-fixed zc Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 21/27] io_uring: allow to pass addr into sendzc Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 22/27] io_uring: sendzc with fixed buffers Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 23/27] io_uring: flush notifiers after sendzc Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 24/27] io_uring: rename IORING_OP_FILES_UPDATE Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 25/27] io_uring: add zc notification flush requests Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 26/27] io_uring: enable managed frags with register buffers Pavel Begunkov
2022-07-07 11:49 ` [PATCH net-next v4 27/27] selftests/io_uring: test zerocopy send Pavel Begunkov
2022-07-08  4:10 ` [PATCH net-next v4 00/27] io_uring " David Ahern

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