From 35089bb203f44e33b6bbb6c4de0b0708f9a48921 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Tue, 13 Jun 2006 22:33:04 -0700 Subject: [PATCH] [TCP]: Add tcp_slow_start_after_idle sysctl. A lot of people have asked for a way to disable tcp_cwnd_restart(), and it seems reasonable to add a sysctl to do that. Signed-off-by: David S. Miller --- Documentation/networking/ip-sysctl.txt | 7 +++++++ include/linux/sysctl.h | 1 + include/net/tcp.h | 1 + net/ipv4/sysctl_net_ipv4.c | 8 ++++++++ net/ipv4/tcp_output.c | 6 +++++- 5 files changed, 22 insertions(+), 1 deletion(-) diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index f12007b..d46338a 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -362,6 +362,13 @@ tcp_workaround_signed_windows - BOOLEAN not receive a window scaling option from them. Default: 0 +tcp_slow_start_after_idle - BOOLEAN + If set, provide RFC2861 behavior and time out the congestion + window after an idle period. An idle period is defined at + the current RTO. If unset, the congestion window will not + be timed out after an idle period. + Default: 1 + IP Variables: ip_local_port_range - 2 INTEGERS diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index 98338ed2..cee944d 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -405,6 +405,7 @@ enum NET_TCP_BASE_MSS=114, NET_IPV4_TCP_WORKAROUND_SIGNED_WINDOWS=115, NET_TCP_DMA_COPYBREAK=116, + NET_TCP_SLOW_START_AFTER_IDLE=117, }; enum { diff --git a/include/net/tcp.h b/include/net/tcp.h index de88c54..bfc71f9 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -227,6 +227,7 @@ extern int sysctl_tcp_abc; extern int sysctl_tcp_mtu_probing; extern int sysctl_tcp_base_mss; extern int sysctl_tcp_workaround_signed_windows; +extern int sysctl_tcp_slow_start_after_idle; extern atomic_t tcp_memory_allocated; extern atomic_t tcp_sockets_allocated; diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index e7fb665..ce4cd5f 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -690,6 +690,14 @@ ctl_table ipv4_table[] = { .proc_handler = &proc_dointvec }, #endif + { + .ctl_name = NET_TCP_SLOW_START_AFTER_IDLE, + .procname = "tcp_slow_start_after_idle", + .data = &sysctl_tcp_slow_start_after_idle, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &proc_dointvec + }, { .ctl_name = 0 } }; diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index f33c9dd..07bb5a2 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -59,6 +59,9 @@ int sysctl_tcp_tso_win_divisor = 3; int sysctl_tcp_mtu_probing = 0; int sysctl_tcp_base_mss = 512; +/* By default, RFC2861 behavior. */ +int sysctl_tcp_slow_start_after_idle = 1; + static void update_send_head(struct sock *sk, struct tcp_sock *tp, struct sk_buff *skb) { @@ -138,7 +141,8 @@ static void tcp_event_data_sent(struct tcp_sock *tp, struct inet_connection_sock *icsk = inet_csk(sk); const u32 now = tcp_time_stamp; - if (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto) + if (sysctl_tcp_slow_start_after_idle && + (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto)) tcp_cwnd_restart(sk, __sk_dst_get(sk)); tp->lsndtime = now; -- 2.7.4