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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180921155154.49489-9-edumazet@google.com>
Date:   Fri, 21 Sep 2018 08:51:53 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>, Van Jacobson <vanj@...gle.com>,
        Neal Cardwell <ncardwell@...gle.com>,
        Yuchung Cheng <ycheng@...gle.com>,
        Soheil Hassas Yeganeh <soheil@...gle.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH net-next 8/9] tcp: switch tcp_internal_pacing() to tcp_wstamp_ns

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 <edumazet@...gle.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