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authorStephen Hemminger <shemminger@osdl.org>2006-06-05 17:30:56 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2006-06-17 21:29:33 -0700
commit738980ffa658c86bd494ebb242ce8e44aff16a9e (patch)
tree92076c6d40f3024d760a5439e564473d70511af0
parenta42e9d6ce89cfd19aee9f990b7231ce697f0d00f (diff)
[TCP]: Limited slow start for Highspeed TCP
Implementation of RFC3742 limited slow start. Added as part of the TCP highspeed congestion control module. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_highspeed.c24
1 files changed, 21 insertions, 3 deletions
diff --git a/net/ipv4/tcp_highspeed.c b/net/ipv4/tcp_highspeed.c
index ba7c63ca5bb..1120245b237 100644
--- a/net/ipv4/tcp_highspeed.c
+++ b/net/ipv4/tcp_highspeed.c
@@ -98,6 +98,10 @@ struct hstcp {
u32 ai;
};
+static int max_ssthresh = 100;
+module_param(max_ssthresh, int, 0644);
+MODULE_PARM_DESC(max_ssthresh, "limited slow start threshold (RFC3742)");
+
static void hstcp_init(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
@@ -119,9 +123,23 @@ static void hstcp_cong_avoid(struct sock *sk, u32 adk, u32 rtt,
if (!tcp_is_cwnd_limited(sk, in_flight))
return;
- if (tp->snd_cwnd <= tp->snd_ssthresh)
- tcp_slow_start(tp);
- else {
+ if (tp->snd_cwnd <= tp->snd_ssthresh) {
+ /* RFC3742: limited slow start
+ * the window is increased by 1/K MSS for each arriving ACK,
+ * for K = int(cwnd/(0.5 max_ssthresh))
+ */
+ if (max_ssthresh > 0 && tp->snd_cwnd > max_ssthresh) {
+ u32 k = max(tp->snd_cwnd / (max_ssthresh >> 1), 1U);
+ if (++tp->snd_cwnd_cnt >= k) {
+ if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+ tp->snd_cwnd++;
+ tp->snd_cwnd_cnt = 0;
+ }
+ } else {
+ if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+ tp->snd_cwnd++;
+ }
+ } else {
/* Update AIMD parameters */
if (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd) {
while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd &&