diff options
| author | John Heffner <jheffner@psc.edu> | 2007-03-25 19:21:45 -0700 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2007-04-25 22:23:19 -0700 |
| commit | 886236c1247ab5e2ad9c73f6e9a652e3ae3c8b07 (patch) | |
| tree | f0ab2d6f6b6c98c6042be100db752c2d492669ae | |
| parent | 5ef814753eb810d900fbd77af7c87f6d04f0e551 (diff) | |
[TCP]: Add RFC3742 Limited Slow-Start, controlled by variable sysctl_tcp_max_ssthresh.
Signed-off-by: John Heffner <jheffner@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/linux/sysctl.h | 1 | ||||
| -rw-r--r-- | include/net/tcp.h | 1 | ||||
| -rw-r--r-- | net/ipv4/sysctl_net_ipv4.c | 8 | ||||
| -rw-r--r-- | net/ipv4/tcp_cong.c | 31 |
4 files changed, 32 insertions, 9 deletions
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index 9a8970bf99a..98e0fd241a2 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -438,6 +438,7 @@ enum NET_CIPSOV4_RBM_STRICTVALID=121, NET_TCP_AVAIL_CONG_CONTROL=122, NET_TCP_ALLOWED_CONG_CONTROL=123, + NET_TCP_MAX_SSTHRESH=124, }; enum { diff --git a/include/net/tcp.h b/include/net/tcp.h index 7fd6b77519c..6d09f5085f6 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -230,6 +230,7 @@ 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 int sysctl_tcp_max_ssthresh; 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 0aa304711a9..d68effe98e8 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -803,6 +803,14 @@ ctl_table ipv4_table[] = { .proc_handler = &proc_allowed_congestion_control, .strategy = &strategy_allowed_congestion_control, }, + { + .ctl_name = NET_TCP_MAX_SSTHRESH, + .procname = "tcp_max_ssthresh", + .data = &sysctl_tcp_max_ssthresh, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &proc_dointvec, + }, { .ctl_name = 0 } }; diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index 34ae3f13483..ccd88407e0c 100644 --- a/net/ipv4/tcp_cong.c +++ b/net/ipv4/tcp_cong.c @@ -12,6 +12,8 @@ #include <linux/list.h> #include <net/tcp.h> +int sysctl_tcp_max_ssthresh = 0; + static DEFINE_SPINLOCK(tcp_cong_list_lock); static LIST_HEAD(tcp_cong_list); @@ -274,10 +276,13 @@ int tcp_set_congestion_control(struct sock *sk, const char *name) /* - * Linear increase during slow start + * Slow start (exponential increase) with + * RFC3742 Limited Slow Start (fast linear increase) support. */ void tcp_slow_start(struct tcp_sock *tp) { + int cnt = 0; + if (sysctl_tcp_abc) { /* RFC3465: Slow Start * TCP sender SHOULD increase cwnd by the number of @@ -286,17 +291,25 @@ void tcp_slow_start(struct tcp_sock *tp) */ if (tp->bytes_acked < tp->mss_cache) return; - - /* We MAY increase by 2 if discovered delayed ack */ - if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache) { - if (tp->snd_cwnd < tp->snd_cwnd_clamp) - tp->snd_cwnd++; - } } + + if (sysctl_tcp_max_ssthresh > 0 && + tp->snd_cwnd > sysctl_tcp_max_ssthresh) + cnt += sysctl_tcp_max_ssthresh>>1; + else + cnt += tp->snd_cwnd; + + /* RFC3465: We MAY increase by 2 if discovered delayed ack */ + if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache) + cnt <<= 1; tp->bytes_acked = 0; - if (tp->snd_cwnd < tp->snd_cwnd_clamp) - tp->snd_cwnd++; + tp->snd_cwnd_cnt += cnt; + while (tp->snd_cwnd_cnt >= tp->snd_cwnd) { + tp->snd_cwnd_cnt -= tp->snd_cwnd; + if (tp->snd_cwnd < tp->snd_cwnd_clamp) + tp->snd_cwnd++; + } } EXPORT_SYMBOL_GPL(tcp_slow_start); |