3 files changed, 33 insertions, 17 deletions

diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
index 02ff2dde9609..a5786e3e2c16 100644
--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c
@@ -128,6 +128,9 @@ static const u32 bbr_probe_rtt_mode_ms = 200;
 /* Skip TSO below the following bandwidth (bits/sec): */
 static const int bbr_min_tso_rate = 1200000;
 
+/* Pace at ~1% below estimated bw, on average, to reduce queue at bottleneck. */
+static const int bbr_pacing_marging_percent = 1;
+
 /* We use a high_gain value of 2/ln(2) because it's the smallest pacing gain
  * that will allow a smoothly increasing pacing rate that will double each RTT
  * and send the same number of packets per RTT that an un-paced, slow-starting
@@ -208,12 +211,10 @@ static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain)
 {
 	unsigned int mss = tcp_sk(sk)->mss_cache;
 
-	if (!tcp_needs_internal_pacing(sk))
-		mss = tcp_mss_to_mtu(sk, mss);
 	rate *= mss;
 	rate *= gain;
 	rate >>= BBR_SCALE;
-	rate *= USEC_PER_SEC;
+	rate *= USEC_PER_SEC / 100 * (100 - bbr_pacing_marging_percent);
 	return rate >> BW_SCALE;
 }
 
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index a87068fa9b1a..2adb719e97b8 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1012,9 +1012,23 @@ static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb)
 	sock_hold(sk);
 }
 
-static void tcp_update_skb_after_send(struct tcp_sock *tp, struct sk_buff *skb)
+static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb)
 {
+	struct tcp_sock *tp = tcp_sk(sk);
+
 	skb->skb_mstamp_ns = tp->tcp_wstamp_ns;
+	if (sk->sk_pacing_status != SK_PACING_NONE) {
+		u32 rate = sk->sk_pacing_rate;
+
+		/* Original sch_fq does not pace first 10 MSS
+		 * Note that tp->data_segs_out overflows after 2^32 packets,
+		 * this is a minor annoyance.
+		 */
+		if (rate != ~0U && rate && tp->data_segs_out >= 10) {
+			tp->tcp_wstamp_ns += div_u64((u64)skb->len * NSEC_PER_SEC, rate);
+			/* TODO: update internal pacing here */
+		}
+	}
 	list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue);
 }
 
@@ -1178,7 +1192,7 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
 		err = net_xmit_eval(err);
 	}
 	if (!err && oskb) {
-		tcp_update_skb_after_send(tp, oskb);
+		tcp_update_skb_after_send(sk, oskb);
 		tcp_rate_skb_sent(sk, oskb);
 	}
 	return err;
@@ -2327,7 +2341,7 @@ 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 */
-			tcp_update_skb_after_send(tp, skb);
+			tcp_update_skb_after_send(sk, skb);
 			goto repair; /* Skip network transmission */
 		}
 
@@ -2902,7 +2916,7 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
 		} tcp_skb_tsorted_restore(skb);
 
 		if (!err) {
-			tcp_update_skb_after_send(tp, skb);
+			tcp_update_skb_after_send(sk, skb);
 			tcp_rate_skb_sent(sk, skb);
 		}
 	} else {
diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index d5185c44e9a5..77692ad6741d 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -491,11 +491,16 @@ begin:
 	}
 
 	skb = f->head;
-	if (unlikely(skb && now < f->time_next_packet &&
-		     !skb_is_tcp_pure_ack(skb))) {
-		head->first = f->next;
-		fq_flow_set_throttled(q, f);
-		goto begin;
+	if (skb && !skb_is_tcp_pure_ack(skb)) {
+		u64 time_next_packet = max_t(u64, ktime_to_ns(skb->tstamp),
+					     f->time_next_packet);
+
+		if (now < time_next_packet) {
+			head->first = f->next;
+			f->time_next_packet = time_next_packet;
+			fq_flow_set_throttled(q, f);
+			goto begin;
+		}
 	}
 
 	skb = fq_dequeue_head(sch, f);
@@ -513,11 +518,7 @@ begin:
 	prefetch(&skb->end);
 	f->credit -= qdisc_pkt_len(skb);
 
-	if (!q->rate_enable)
-		goto out;
-
-	/* Do not pace locally generated ack packets */
-	if (skb_is_tcp_pure_ack(skb))
+	if (ktime_to_ns(skb->tstamp) || !q->rate_enable)
 		goto out;
 
 	rate = q->flow_max_rate;