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Commit 69e996c5 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: add tp->tcp_mstamp field 



We want to use precise timestamps in TCP stack, but we do not
want to call possibly expensive kernel time services too often.

tp->tcp_mstamp is guaranteed to be updated once per incoming packet.

We will use it in the following patches, removing specific
skb_mstamp_get() calls, and removing ack_time from
struct tcp_sacktag_state.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 038a3e85

include/linux/tcp.h

+1 −0
Original line number Diff line number Diff line
@@ -240,6 +240,7 @@ struct tcp_sock { 
	u32	tlp_high_seq;	/* snd_nxt at the time of TLP retransmit. */



/* RTT measurement */

	struct skb_mstamp tcp_mstamp; /* most recent packet received/sent */

	u32	srtt_us;	/* smoothed round trip time << 3 in usecs */

	u32	mdev_us;	/* medium deviation			*/

	u32	mdev_max_us;	/* maximal mdev for the last rtt period	*/

net/ipv4/tcp_input.c

+3 −0
Original line number Diff line number Diff line
@@ -5362,6 +5362,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 
{

	struct tcp_sock *tp = tcp_sk(sk);



	skb_mstamp_get(&tp->tcp_mstamp);

	if (unlikely(!sk->sk_rx_dst))

		inet_csk(sk)->icsk_af_ops->sk_rx_dst_set(sk, skb);

	/*
@@ -5922,6 +5923,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) 


	case TCP_SYN_SENT:

		tp->rx_opt.saw_tstamp = 0;

		skb_mstamp_get(&tp->tcp_mstamp);

		queued = tcp_rcv_synsent_state_process(sk, skb, th);

		if (queued >= 0)

			return queued;
@@ -5933,6 +5935,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) 
		return 0;

	}



	skb_mstamp_get(&tp->tcp_mstamp);

	tp->rx_opt.saw_tstamp = 0;

	req = tp->fastopen_rsk;

	if (req) {