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From: Eric Dumazet <edumazet@google.com>
To: "David S . Miller" <davem@davemloft.net>
Cc: netdev <netdev@vger.kernel.org>, Van Jacobson <vanj@google.com>,
	Neal Cardwell <ncardwell@google.com>,
	Yuchung Cheng <ycheng@google.com>,
	Soheil Hassas Yeganeh <soheil@google.com>,
	Willem de Bruijn <willemb@google.com>,
	Eric Dumazet <edumazet@google.com>,
	Eric Dumazet <eric.dumazet@gmail.com>
Subject: [PATCH net-next 5/9] tcp: provide earliest departure time in skb->tstamp
Date: Fri, 21 Sep 2018 08:51:50 -0700	[thread overview]
Message-ID: <20180921155154.49489-6-edumazet@google.com> (raw)
In-Reply-To: <20180921155154.49489-1-edumazet@google.com>

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: Eric Dumazet <edumazet@google.com>
---
 include/linux/skbuff.h |  2 +-
 include/net/tcp.h      |  6 +++---
 net/ipv4/syncookies.c  |  2 +-
 net/ipv4/tcp.c         |  2 +-
 net/ipv4/tcp_output.c  | 13 ++++++-------
 net/ipv4/tcp_timer.c   |  2 +-
 6 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index e3a53ca4a9b51b84b7d75ce87485d4d9109a4cf2..86f337e9a81d5eff360335a19ab09f26ae48fca8 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -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
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 370198fdc65d3e863104665e20faefd0e5a09b92..ff15d8e0d525715b17671e64f6abdead9df0a8f3 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -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)
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index c3387dfd725bf99bcddefb9fb4f1dc98f5dd7f23..606f868d9f3fde1c3140aa7eecde87d2ec32b5f2 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -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);
 }
 
 
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 67670fac7c8de510df351fe3a835b554cc4759a9..69c236943f56bd0749e5efb18de97e69898f1bde 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -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)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 5a8105e84f7c1a876bbd15e8050c2574c1fbe162..957f7a0e21c06cae9f0d3bed57017bbc0a36c880 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -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)
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 7fdf222a0bdfe9775970082f6b5dcdcc82b2ae1a..61023d50cd604d5e19464a32c33b65d29c75c81e 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -360,7 +360,7 @@ static void tcp_probe_timer(struct sock *sk)
 	 */
 	start_ts = tcp_skb_timestamp(skb);
 	if (!start_ts)
-		skb->skb_mstamp = tp->tcp_mstamp;
+		skb->skb_mstamp_ns = tp->tcp_wstamp_ns;
 	else if (icsk->icsk_user_timeout &&
 		 (s32)(tcp_time_stamp(tp) - start_ts) > icsk->icsk_user_timeout)
 		goto abort;
-- 
2.19.0.444.g18242da7ef-goog

  parent reply	other threads:[~2018-09-21 21:41 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-21 15:51 [PATCH net-next 0/9] tcp: switch to Early Departure Time model Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 1/9] tcp: switch tcp_clock_ns() to CLOCK_TAI base Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 2/9] tcp: introduce tcp_skb_timestamp_us() helper Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 3/9] net_sched: sch_fq: switch to CLOCK_TAI Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 4/9] tcp: add tcp_wstamp_ns socket field Eric Dumazet
2018-09-21 15:51 ` Eric Dumazet [this message]
2018-09-21 15:51 ` [PATCH net-next 6/9] tcp: switch internal pacing timer to CLOCK_TAI Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 7/9] tcp: switch tcp and sch_fq to new earliest departure time model Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 8/9] tcp: switch tcp_internal_pacing() to tcp_wstamp_ns Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 9/9] net_sched: sch_fq: remove dead code dealing with retransmits Eric Dumazet

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