sock: avoid dirtying sk_stamp, if possible (6c7c98ba) · Commits · 戴 / test

sock_recv_ts_and_drops() unconditionally set sk->sk_stamp for every packet, even if the SOCK_TIMESTAMP flag is not set in the related socket. If selinux is enabled, this cause a cache miss for every packet since sk->sk_stamp and sk->sk_security share the same cacheline. With this change sk_stamp is set only if the SOCK_TIMESTAMP flag is set, and is cleared for the first packet, so that the user perceived behavior is unchanged. This gives up to 5% speed-up under udp-flood with small packets. Signed-off-by:

Paolo Abeni <pabeni@redhat.com> Acked-by:

Eric Dumazet <edumazet@google.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

include/net/sock.h

+4 −1

Original line number	Diff line number	Diff line
		@@ -2239,6 +2239,7 @@ sock_recv_timestamp(struct msghdr msg, struct sock sk, struct sk_buff *skb)
		void __sock_recv_ts_and_drops(struct msghdr msg, struct sock sk,
		struct sk_buff *skb);

		#define SK_DEFAULT_STAMP (-1L * NSEC_PER_SEC)
		static inline void sock_recv_ts_and_drops(struct msghdr msg, struct sock sk,
		struct sk_buff *skb)
		{
		@@ -2249,8 +2250,10 @@ static inline void sock_recv_ts_and_drops(struct msghdr msg, struct sock sk,

		if (sk->sk_flags & FLAGS_TS_OR_DROPS \|\| sk->sk_tsflags & TSFLAGS_ANY)
		__sock_recv_ts_and_drops(msg, sk, skb);
		else
		else if (unlikely(sk->sk_flags & SOCK_TIMESTAMP))
		sk->sk_stamp = skb->tstamp;
		else if (unlikely(sk->sk_stamp == SK_DEFAULT_STAMP))
		sk->sk_stamp = 0;
		}

		void __sock_tx_timestamp(__u16 tsflags, __u8 *tx_flags);

net/core/sock.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2613,7 +2613,7 @@ void sock_init_data(struct socket sock, struct sock sk)
		sk->sk_rcvtimeo = MAX_SCHEDULE_TIMEOUT;
		sk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;

		sk->sk_stamp = ktime_set(-1L, 0);
		sk->sk_stamp = SK_DEFAULT_STAMP;

		#ifdef CONFIG_NET_RX_BUSY_POLL
		sk->sk_napi_id = 0;

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