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Commit d3edd06e authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: provide earliest departure time in skb->tstamp 



Switch internal TCP skb->skb_mstamp to skb->skb_mstamp_ns,
from usec units to nsec units.

Do not clear skb->tstamp before entering IP stacks in TX,
so that qdisc or devices can implement pacing based on the
earliest departure time instead of socket sk->sk_pacing_rate

Packets are fed with tcp_wstamp_ns, and following patch
will update tcp_wstamp_ns when both TCP and sch_fq switch to
the earliest departure time mechanism.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9799ccb0

include/linux/skbuff.h

+1 −1
Original line number Diff line number Diff line
@@ -689,7 +689,7 @@ struct sk_buff { 


	union {

		ktime_t		tstamp;

		u64		skb_mstamp;

		u64		skb_mstamp_ns; /* earliest departure time */

	};

	/*

	 * This is the control buffer. It is free to use for every

include/net/tcp.h

+3 −3
Original line number Diff line number Diff line
@@ -761,13 +761,13 @@ static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0) 


static inline u32 tcp_skb_timestamp(const struct sk_buff *skb)

{

	return div_u64(skb->skb_mstamp, USEC_PER_SEC / TCP_TS_HZ);

	return div_u64(skb->skb_mstamp_ns, NSEC_PER_SEC / TCP_TS_HZ);

}



/* provide the departure time in us unit */

static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)

{

	return skb->skb_mstamp;

	return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);

}
@@ -813,7 +813,7 @@ struct tcp_skb_cb { 
#define TCPCB_SACKED_RETRANS	0x02	/* SKB retransmitted		*/

#define TCPCB_LOST		0x04	/* SKB is lost			*/

#define TCPCB_TAGBITS		0x07	/* All tag bits			*/

#define TCPCB_REPAIRED		0x10	/* SKB repaired (no skb_mstamp)	*/

#define TCPCB_REPAIRED		0x10	/* SKB repaired (no skb_mstamp_ns)	*/

#define TCPCB_EVER_RETRANS	0x80	/* Ever retransmitted frame	*/

#define TCPCB_RETRANS		(TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \

				TCPCB_REPAIRED)

net/ipv4/syncookies.c

+1 −1
Original line number Diff line number Diff line
@@ -88,7 +88,7 @@ u64 cookie_init_timestamp(struct request_sock *req) 
		ts <<= TSBITS;

		ts |= options;

	}

	return (u64)ts * (USEC_PER_SEC / TCP_TS_HZ);

	return (u64)ts * (NSEC_PER_SEC / TCP_TS_HZ);

}

net/ipv4/tcp.c

+1 −1
Original line number Diff line number Diff line
@@ -1295,7 +1295,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) 
			copy = size_goal;



			/* All packets are restored as if they have

			 * already been sent. skb_mstamp isn't set to

			 * already been sent. skb_mstamp_ns isn't set to

			 * avoid wrong rtt estimation.

			 */

			if (tp->repair)

net/ipv4/tcp_output.c

+6 −7
Original line number Diff line number Diff line
@@ -1014,7 +1014,7 @@ static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb) 


static void tcp_update_skb_after_send(struct tcp_sock *tp, struct sk_buff *skb)

{

	skb->skb_mstamp = tp->tcp_mstamp;

	skb->skb_mstamp_ns = tp->tcp_wstamp_ns;

	list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue);

}
@@ -1061,7 +1061,7 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, 
		if (unlikely(!skb))

			return -ENOBUFS;

	}

	skb->skb_mstamp = tp->tcp_mstamp;

	skb->skb_mstamp_ns = tp->tcp_wstamp_ns;



	inet = inet_sk(sk);

	tcb = TCP_SKB_CB(skb);
@@ -1165,8 +1165,7 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, 
	skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb);

	skb_shinfo(skb)->gso_size = tcp_skb_mss(skb);



	/* Our usage of tstamp should remain private */

	skb->tstamp = 0;

	/* Leave earliest departure time in skb->tstamp (skb->skb_mstamp_ns) */



	/* Cleanup our debris for IP stacks */

	memset(skb->cb, 0, max(sizeof(struct inet_skb_parm),
@@ -3221,10 +3220,10 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 
	memset(&opts, 0, sizeof(opts));

#ifdef CONFIG_SYN_COOKIES

	if (unlikely(req->cookie_ts))

		skb->skb_mstamp = cookie_init_timestamp(req);

		skb->skb_mstamp_ns = cookie_init_timestamp(req);

	else

#endif

		skb->skb_mstamp = tcp_clock_us();

		skb->skb_mstamp_ns = tcp_clock_ns();



#ifdef CONFIG_TCP_MD5SIG

	rcu_read_lock();
@@ -3440,7 +3439,7 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) 


	err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation);



	syn->skb_mstamp = syn_data->skb_mstamp;

	syn->skb_mstamp_ns = syn_data->skb_mstamp_ns;



	/* Now full SYN+DATA was cloned and sent (or not),

	 * remove the SYN from the original skb (syn_data)