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Date: Thu, 4 Apr 2013 18:16:00 +0800
From: Cong Wang <amwang@...hat.com>
To: netdev@...r.kernel.org
Cc: Eric Dumazet <eric.dumazet@...il.com>,
Rick Jones <rick.jones2@...com>,
Stephen Hemminger <shemminger@...tta.com>,
"David S. Miller" <davem@...emloft.net>,
Thomas Graf <tgraf@...g.ch>,
David Laight <David.Laight@...LAB.COM>,
Cong Wang <amwang@...hat.com>
Subject: [Patch net-next] tcp: add a global sysctl to control TCP delayed ack
From: Cong Wang <amwang@...hat.com>
Change from RFC:
* make the sysctl per netns
According to previous discussion, it seems there is no
reasonable heuristics.
Similar to TCP_QUICK_ACK option, but for people who can't
modify the source code and still wants to control
TCP delayed ACK behavior.
David, do you still have any objection?
Cc: Eric Dumazet <eric.dumazet@...il.com>
Cc: Rick Jones <rick.jones2@...com>
Cc: Stephen Hemminger <shemminger@...tta.com>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Thomas Graf <tgraf@...g.ch>
CC: David Laight <David.Laight@...LAB.COM>
Signed-off-by: Cong Wang <amwang@...hat.com>
---
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index f98ca63..9b39681 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -572,6 +572,11 @@ tcp_challenge_ack_limit - INTEGER
in RFC 5961 (Improving TCP's Robustness to Blind In-Window Attacks)
Default: 100
+tcp_quick_ack - BOOLEAN
+ Globally enables or disables TCP delayed ACK. The applications
+ can still change the quick ACK mode by TCP_QUICK_ACK option.
+ Default: off
+
UDP variables:
udp_mem - vector of 3 INTEGERs: min, pressure, max
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 2ba9de8..f03298a 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -63,6 +63,7 @@ struct netns_ipv4 {
int sysctl_icmp_errors_use_inbound_ifaddr;
int sysctl_tcp_ecn;
+ int sysctl_tcp_quick_ack;
kgid_t sysctl_ping_group_range[2];
long sysctl_tcp_mem[3];
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index fa2f63f..1db1780 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -837,6 +837,13 @@ static struct ctl_table ipv4_net_table[] = {
.mode = 0644,
.proc_handler = ipv4_tcp_mem,
},
+ {
+ .procname = "tcp_quick_ack",
+ .data = &init_net.ipv4.sysctl_tcp_quick_ack,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
{ }
};
@@ -866,6 +873,8 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
&net->ipv4.sysctl_ping_group_range;
table[7].data =
&net->ipv4.sysctl_tcp_ecn;
+ table[9].data =
+ &net->ipv4.sysctl_tcp_quick_ack;
/* Don't export sysctls to unprivileged users */
if (net->user_ns != &init_user_ns)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 6d9ca35..a1b44f3 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3781,7 +3781,8 @@ static void tcp_fin(struct sock *sk)
case TCP_ESTABLISHED:
/* Move to CLOSE_WAIT */
tcp_set_state(sk, TCP_CLOSE_WAIT);
- inet_csk(sk)->icsk_ack.pingpong = 1;
+ if (!sock_net(sk)->ipv4.sysctl_tcp_quick_ack)
+ inet_csk(sk)->icsk_ack.pingpong = 1;
break;
case TCP_CLOSE_WAIT:
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index af354c98..130fc99 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -169,8 +169,9 @@ static void tcp_event_data_sent(struct tcp_sock *tp,
/* If it is a reply for ato after last received
* packet, enter pingpong mode.
*/
- if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato)
- icsk->icsk_ack.pingpong = 1;
+ if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato &&
+ !sock_net(sk)->ipv4.sysctl_tcp_quick_ack)
+ icsk->icsk_ack.pingpong = 1;
}
/* Account for an ACK we sent. */
--
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