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Commit 6c7c98ba authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
Browse files

sock: avoid dirtying sk_stamp, if possible 



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: default avatarPaolo Abeni <pabeni@redhat.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7801a322

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;