[PATCH net-next 8/9] tcp: switch tcp_internal_pacing() to tcp_wstamp_ns

[Eric Dumazet]

Now TCP keeps track of tcp_wstamp_ns, recording the earliest
departure time of next packet, we can remove duplicate code
from tcp_internal_pacing()

This removes one ktime_get_tai_ns() call, and a divide.

Signed-off-by: Eric Dumazet <eduma...@google.com>
---
 net/ipv4/tcp_output.c | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 
2adb719e97b89021becfa1243d33c87df6cdf8a5..fe7855b090e4feed6a7d1ba6ee874cdb23a9bd0c
 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -993,21 +993,12 @@ enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer)
        return HRTIMER_NORESTART;
 }
 
-static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb)
+static void tcp_internal_pacing(struct sock *sk)
 {
-       u64 len_ns;
-       u32 rate;
-
        if (!tcp_needs_internal_pacing(sk))
                return;
-       rate = sk->sk_pacing_rate;
-       if (!rate || rate == ~0U)
-               return;
-
-       len_ns = (u64)skb->len * NSEC_PER_SEC;
-       do_div(len_ns, rate);
        hrtimer_start(&tcp_sk(sk)->pacing_timer,
-                     ktime_add_ns(ktime_get_tai_ns(), len_ns),
+                     ns_to_ktime(tcp_sk(sk)->tcp_wstamp_ns),
                      HRTIMER_MODE_ABS_PINNED_SOFT);
        sock_hold(sk);
 }
@@ -1026,7 +1017,8 @@ static void tcp_update_skb_after_send(struct sock *sk, 
struct sk_buff *skb)
                 */
                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 */
+
+                       tcp_internal_pacing(sk);
                }
        }
        list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue);
@@ -1167,7 +1159,6 @@ static int __tcp_transmit_skb(struct sock *sk, struct 
sk_buff *skb,
                tcp_event_data_sent(tp, sk);
                tp->data_segs_out += tcp_skb_pcount(skb);
                tp->bytes_sent += skb->len - tcp_header_size;
-               tcp_internal_pacing(sk, skb);
        }
 
        if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq)
-- 
2.19.0.444.g18242da7ef-goog