fedora core 6 1.2949 + vserver 2.2.0

[linux-2.6.git] / net / ipv4 / tcp_highspeed.c

diff --git a/net/ipv4/tcp_highspeed.c b/net/ipv4/tcp_highspeed.c
index e0e9d13..c4fc811 100644 (file)
--- a/net/ipv4/tcp_highspeed.c
+++ b/net/ipv4/tcp_highspeed.c
@@ -6,7 +6,6 @@
  * John Heffner <jheffner@psc.edu>
  */
 
-#include <linux/config.h>
 #include <linux/module.h>
 #include <net/tcp.h>
 
@@ -98,6 +97,10 @@ 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);
@@ -119,26 +122,46 @@ 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 {
-               /* Update AIMD parameters */
+       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.
+                *
+                * We want to guarantee that:
+                *     hstcp_aimd_vals[ca->ai-1].cwnd <
+                *     snd_cwnd <=
+                *     hstcp_aimd_vals[ca->ai].cwnd
+                */
                if (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd) {
                        while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd &&
                               ca->ai < HSTCP_AIMD_MAX - 1)
                                ca->ai++;
-               } else if (tp->snd_cwnd < hstcp_aimd_vals[ca->ai].cwnd) {
-                       while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd &&
-                              ca->ai > 0)
+               } else if (ca->ai && tp->snd_cwnd <= hstcp_aimd_vals[ca->ai-1].cwnd) {
+                       while (ca->ai && tp->snd_cwnd <= hstcp_aimd_vals[ca->ai-1].cwnd)
                                ca->ai--;
                }
 
                /* Do additive increase */
                if (tp->snd_cwnd < tp->snd_cwnd_clamp) {
-                       tp->snd_cwnd_cnt += ca->ai;
+                       /* cwnd = cwnd + a(w) / cwnd */
+                       tp->snd_cwnd_cnt += ca->ai + 1;
                        if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
-                               tp->snd_cwnd++;
                                tp->snd_cwnd_cnt -= tp->snd_cwnd;
+                               tp->snd_cwnd++;
                        }
                }
        }
@@ -166,7 +189,7 @@ static struct tcp_congestion_ops tcp_highspeed = {
 
 static int __init hstcp_register(void)
 {
-       BUG_ON(sizeof(struct hstcp) > ICSK_CA_PRIV_SIZE);
+       BUILD_BUG_ON(sizeof(struct hstcp) > ICSK_CA_PRIV_SIZE);
        return tcp_register_congestion_control(&tcp_highspeed);
 }