From 8a3854c7b8e4532063b14bed34115079b7d0cb36 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Thu, 20 Oct 2022 19:48:52 +0200 Subject: udp: track the forward memory release threshold in an hot cacheline When the receiver process and the BH runs on different cores, udp_rmem_release() experience a cache miss while accessing sk_rcvbuf, as the latter shares the same cacheline with sk_forward_alloc, written by the BH. With this patch, UDP tracks the rcvbuf value and its update via custom SOL_SOCKET socket options, and copies the forward memory threshold value used by udp_rmem_release() in a different cacheline, already accessed by the above function and uncontended. Since the UDP socket init operation grown a bit, factor out the common code between v4 and v6 in a shared helper. Overall the above give a 10% peek throughput increase under UDP flood. Signed-off-by: Paolo Abeni Reviewed-by: Eric Dumazet Acked-by: Kuniyuki Iwashima Signed-off-by: David S. Miller --- include/linux/udp.h | 3 +++ include/net/udp.h | 9 +++++++++ 2 files changed, 12 insertions(+) (limited to 'include') diff --git a/include/linux/udp.h b/include/linux/udp.h index e96da4157d04..5cdba00a904a 100644 --- a/include/linux/udp.h +++ b/include/linux/udp.h @@ -87,6 +87,9 @@ struct udp_sock { /* This field is dirtied by udp_recvmsg() */ int forward_deficit; + + /* This fields follows rcvbuf value, and is touched by udp_recvmsg */ + int forward_threshold; }; #define UDP_MAX_SEGMENTS (1 << 6UL) diff --git a/include/net/udp.h b/include/net/udp.h index fee053bcd17c..de4b528522bb 100644 --- a/include/net/udp.h +++ b/include/net/udp.h @@ -174,6 +174,15 @@ INDIRECT_CALLABLE_DECLARE(int udpv6_rcv(struct sk_buff *)); struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, netdev_features_t features, bool is_ipv6); +static inline void udp_lib_init_sock(struct sock *sk) +{ + struct udp_sock *up = udp_sk(sk); + + skb_queue_head_init(&up->reader_queue); + up->forward_threshold = sk->sk_rcvbuf >> 2; + set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags); +} + /* hash routines shared between UDPv4/6 and UDP-Litev4/6 */ static inline int udp_lib_hash(struct sock *sk) { -- cgit v1.2.3