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authorEric Dumazet <edumazet@google.com>2018-05-22 01:08:57 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-08-09 13:20:32 +0300
commitd8c80fae49027ee5fce46df8f9bcc92d4b855771 (patch)
tree8749eec4a5d53ec50d64681b107e5e7e486582e0 /net/ipv4
parentc4af434936605e294485f220d0f92e956ccbd58d (diff)
downloadlinux-d8c80fae49027ee5fce46df8f9bcc92d4b855771.tar.xz
tcp: do not aggressively quick ack after ECN events
[ Upstream commit 522040ea5fdd1c33bbf75e1d7c7c0422b96a94ef ] ECN signals currently forces TCP to enter quickack mode for up to 16 (TCP_MAX_QUICKACKS) following incoming packets. We believe this is not needed, and only sending one immediate ack for the current packet should be enough. This should reduce the extra load noticed in DCTCP environments, after congestion events. This is part 2 of our effort to reduce pure ACK packets. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/tcp_input.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index f1deaa323c1f..8b7e946094a4 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -230,7 +230,7 @@ static void __tcp_ecn_check_ce(struct tcp_sock *tp, const struct sk_buff *skb)
* it is probably a retransmit.
*/
if (tp->ecn_flags & TCP_ECN_SEEN)
- tcp_enter_quickack_mode((struct sock *)tp, TCP_MAX_QUICKACKS);
+ tcp_enter_quickack_mode((struct sock *)tp, 1);
break;
case INET_ECN_CE:
if (tcp_ca_needs_ecn((struct sock *)tp))
@@ -238,7 +238,7 @@ static void __tcp_ecn_check_ce(struct tcp_sock *tp, const struct sk_buff *skb)
if (!(tp->ecn_flags & TCP_ECN_DEMAND_CWR)) {
/* Better not delay acks, sender can have a very low cwnd */
- tcp_enter_quickack_mode((struct sock *)tp, TCP_MAX_QUICKACKS);
+ tcp_enter_quickack_mode((struct sock *)tp, 1);
tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
}
tp->ecn_flags |= TCP_ECN_SEEN;