[TCP]: TCP Illinois update.

[~andy/linux] / net / ipv4 / tcp_cong.c

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 34ae3f13483a6e37b65402e3318bd635b716e460..ccd88407e0cdf56e4154c858b120605756f05c14 100644 (file)
--- 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);