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Commit 385e2070 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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tcp: use tp->tcp_mstamp in output path 



Idea is to later convert tp->tcp_mstamp to a full u64 counter
using usec resolution, so that we can later have fine
grained TCP TS clock (RFC 7323), regardless of HZ value.

We try to refresh tp->tcp_mstamp only when necessary.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9d4f97f9

net/ipv4/tcp_ipv4.c

+1 −0
Original line number Diff line number Diff line
@@ -483,6 +483,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info) 
		skb = tcp_write_queue_head(sk);

		BUG_ON(!skb);



		skb_mstamp_get(&tp->tcp_mstamp);

		remaining = icsk->icsk_rto -

			    min(icsk->icsk_rto,

				tcp_time_stamp - tcp_skb_timestamp(skb));

net/ipv4/tcp_output.c

+11 −10
Original line number Diff line number Diff line
@@ -997,8 +997,8 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, 
	BUG_ON(!skb || !tcp_skb_pcount(skb));

	tp = tcp_sk(sk);



	skb->skb_mstamp = tp->tcp_mstamp;

	if (clone_it) {

		skb_mstamp_get(&skb->skb_mstamp);

		TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq

			- tp->snd_una;

		tcp_rate_skb_sent(sk, skb);
@@ -1906,7 +1906,6 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 
	const struct inet_connection_sock *icsk = inet_csk(sk);

	u32 age, send_win, cong_win, limit, in_flight;

	struct tcp_sock *tp = tcp_sk(sk);

	struct skb_mstamp now;

	struct sk_buff *head;

	int win_divisor;
@@ -1962,8 +1961,8 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 
	}



	head = tcp_write_queue_head(sk);

	skb_mstamp_get(&now);

	age = skb_mstamp_us_delta(&now, &head->skb_mstamp);



	age = skb_mstamp_us_delta(&tp->tcp_mstamp, &head->skb_mstamp);

	/* If next ACK is likely to come too late (half srtt), do not defer */

	if (age < (tp->srtt_us >> 4))

		goto send_now;
@@ -2280,6 +2279,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 
	}



	max_segs = tcp_tso_segs(sk, mss_now);

	skb_mstamp_get(&tp->tcp_mstamp);

	while ((skb = tcp_send_head(sk))) {

		unsigned int limit;
@@ -2291,7 +2291,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, 


		if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) {

			/* "skb_mstamp" is used as a start point for the retransmit timer */

			skb_mstamp_get(&skb->skb_mstamp);

			skb->skb_mstamp = tp->tcp_mstamp;

			goto repair; /* Skip network transmission */

		}
@@ -2879,7 +2879,7 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 
		     skb_headroom(skb) >= 0xFFFF)) {

		struct sk_buff *nskb;



		skb_mstamp_get(&skb->skb_mstamp);

		skb->skb_mstamp = tp->tcp_mstamp;

		nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC);

		err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) :

			     -ENOBUFS;
@@ -3095,7 +3095,7 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority) 
	skb_reserve(skb, MAX_TCP_HEADER);

	tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk),

			     TCPHDR_ACK | TCPHDR_RST);

	skb_mstamp_get(&skb->skb_mstamp);

	skb_mstamp_get(&tcp_sk(sk)->tcp_mstamp);

	/* Send it off. */

	if (tcp_transmit_skb(sk, skb, 0, priority))

		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED);
@@ -3453,7 +3453,8 @@ int tcp_connect(struct sock *sk) 
		return -ENOBUFS;



	tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN);

	tp->retrans_stamp = tcp_time_stamp;

	skb_mstamp_get(&tp->tcp_mstamp);

	tp->retrans_stamp = tp->tcp_mstamp.stamp_jiffies;

	tcp_connect_queue_skb(sk, buff);

	tcp_ecn_send_syn(sk, buff);
@@ -3572,7 +3573,6 @@ void tcp_send_ack(struct sock *sk) 
	skb_set_tcp_pure_ack(buff);



	/* Send it off, this clears delayed acks for us. */

	skb_mstamp_get(&buff->skb_mstamp);

	tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0);

}

EXPORT_SYMBOL_GPL(tcp_send_ack);
@@ -3606,15 +3606,16 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) 
	 * send it.

	 */

	tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK);

	skb_mstamp_get(&skb->skb_mstamp);

	NET_INC_STATS(sock_net(sk), mib);

	return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0);

}



/* Called from setsockopt( ... TCP_REPAIR ) */

void tcp_send_window_probe(struct sock *sk)

{

	if (sk->sk_state == TCP_ESTABLISHED) {

		tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1;

		skb_mstamp_get(&tcp_sk(sk)->tcp_mstamp);

		tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE);

	}

}

net/ipv4/tcp_recovery.c

+0 −1
Original line number Diff line number Diff line
@@ -166,7 +166,6 @@ void tcp_rack_reo_timeout(struct sock *sk) 
	u32 timeout, prior_inflight;



	prior_inflight = tcp_packets_in_flight(tp);

	skb_mstamp_get(&tp->tcp_mstamp);

	tcp_rack_detect_loss(sk, &timeout);

	if (prior_inflight != tcp_packets_in_flight(tp)) {

		if (inet_csk(sk)->icsk_ca_state != TCP_CA_Recovery) {

net/ipv4/tcp_timer.c

+2 −1
Original line number Diff line number Diff line
@@ -339,7 +339,7 @@ static void tcp_probe_timer(struct sock *sk) 
	 */

	start_ts = tcp_skb_timestamp(tcp_send_head(sk));

	if (!start_ts)

		skb_mstamp_get(&tcp_send_head(sk)->skb_mstamp);

		tcp_send_head(sk)->skb_mstamp = tp->tcp_mstamp;

	else if (icsk->icsk_user_timeout &&

		 (s32)(tcp_time_stamp - start_ts) > icsk->icsk_user_timeout)

		goto abort;
@@ -561,6 +561,7 @@ void tcp_write_timer_handler(struct sock *sk) 
		goto out;

	}



	skb_mstamp_get(&tcp_sk(sk)->tcp_mstamp);

	event = icsk->icsk_pending;



	switch (event) {