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From: Alexander Lobakin <alobakin@pm.me>
To: "David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andriin@fb.com>,
	Alexander Lobakin <alobakin@pm.me>,
	Eric Dumazet <edumazet@google.com>, Wei Wang <weiwan@google.com>,
	Cong Wang <cong.wang@bytedance.com>,
	Taehee Yoo <ap420073@gmail.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH net-next 2/4] gro: don't dereference napi->gro_hash[x] multiple times in dev_gro_receive()
Date: Fri, 12 Mar 2021 16:21:58 +0000	[thread overview]
Message-ID: <20210312162127.239795-3-alobakin@pm.me> (raw)
In-Reply-To: <20210312162127.239795-1-alobakin@pm.me>

GRO bucket index doesn't change through the entire function.
Store a pointer to the corresponding bucket on stack once and use
it later instead of dereferencing again and again.

Signed-off-by: Alexander Lobakin <alobakin@pm.me>
---
 net/core/dev.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index adc42ba7ffd8..ee124aecb8a2 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5957,6 +5957,7 @@ static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 {
 	u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
+	struct gro_list *gro_list = &napi->gro_hash[bucket];
 	struct list_head *head = &offload_base;
 	struct packet_offload *ptype;
 	__be16 type = skb->protocol;
@@ -6024,7 +6025,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
 	if (pp) {
 		skb_list_del_init(pp);
 		napi_gro_complete(napi, pp);
-		napi->gro_hash[bucket].count--;
+		gro_list->count--;
 	}

 	if (same_flow)
@@ -6033,10 +6034,10 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
 	if (NAPI_GRO_CB(skb)->flush)
 		goto normal;

-	if (unlikely(napi->gro_hash[bucket].count >= MAX_GRO_SKBS)) {
+	if (unlikely(gro_list->count >= MAX_GRO_SKBS)) {
 		gro_flush_oldest(napi, gro_head);
 	} else {
-		napi->gro_hash[bucket].count++;
+		gro_list->count++;
 	}
 	NAPI_GRO_CB(skb)->count = 1;
 	NAPI_GRO_CB(skb)->age = jiffies;
@@ -6050,7 +6051,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
 	if (grow > 0)
 		gro_pull_from_frag0(skb, grow);
 ok:
-	if (napi->gro_hash[bucket].count) {
+	if (gro_list->count) {
 		if (!test_bit(bucket, &napi->gro_bitmask))
 			__set_bit(bucket, &napi->gro_bitmask);
 	} else if (test_bit(bucket, &napi->gro_bitmask)) {
--
2.30.2



  parent reply	other threads:[~2021-03-12 16:22 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-12 16:21 [PATCH net-next 0/4] gro: micro-optimize dev_gro_receive() Alexander Lobakin
2021-03-12 16:21 ` [PATCH net-next 1/4] gro: give 'hash' variable in dev_gro_receive() a less confusing name Alexander Lobakin
2021-03-12 16:21 ` Alexander Lobakin [this message]
2021-03-12 16:47   ` [PATCH net-next 2/4] gro: don't dereference napi->gro_hash[x] multiple times in dev_gro_receive() Eric Dumazet
2021-03-12 18:36     ` Alexander Lobakin
2021-03-12 16:22 ` [PATCH net-next 3/4] gro: simplify gro_list_prepare() Alexander Lobakin
2021-03-12 16:22 ` [PATCH net-next 4/4] gro: improve flow distribution across GRO buckets in dev_gro_receive() Alexander Lobakin
2021-03-12 16:33   ` Eric Dumazet
2021-03-12 18:28     ` Alexander Lobakin

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