linux 2.6.16.38 w/ vs2.0.3-rc1

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

diff --git a/net/ipv4/tcp_htcp.c b/net/ipv4/tcp_htcp.c
index 6edfe5e..128de4d 100644 (file)
--- a/net/ipv4/tcp_htcp.c
+++ b/net/ipv4/tcp_htcp.c
@@ -6,6 +6,7 @@
  * http://www.hamilton.ie/net/htcp3.pdf
  */
 
+#include <linux/config.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <net/tcp.h>
@@ -26,12 +27,12 @@ struct htcp {
        u16     alpha;          /* Fixed point arith, << 7 */
        u8      beta;           /* Fixed point arith, << 7 */
        u8      modeswitch;     /* Delay modeswitch until we had at least one congestion event */
-       u32     last_cong;      /* Time since last congestion event end */
-       u32     undo_last_cong;
-       u16     pkts_acked;
-       u32     packetcount;
+       u8      ccount;         /* Number of RTTs since last congestion event */
+       u8      undo_ccount;
+       u16     packetcount;
        u32     minRTT;
        u32     maxRTT;
+       u32     snd_cwnd_cnt2;
 
        u32     undo_maxRTT;
        u32     undo_old_maxB;
@@ -44,30 +45,21 @@ struct htcp {
        u32     lasttime;
 };
 
-static inline u32 htcp_cong_time(struct htcp *ca)
-{
-       return jiffies - ca->last_cong;
-}
-
-static inline u32 htcp_ccount(struct htcp *ca)
-{
-       return htcp_cong_time(ca)/ca->minRTT;
-}
-
 static inline void htcp_reset(struct htcp *ca)
 {
-       ca->undo_last_cong = ca->last_cong;
+       ca->undo_ccount = ca->ccount;
        ca->undo_maxRTT = ca->maxRTT;
        ca->undo_old_maxB = ca->old_maxB;
 
-       ca->last_cong = jiffies;
+       ca->ccount = 0;
+       ca->snd_cwnd_cnt2 = 0;
 }
 
 static u32 htcp_cwnd_undo(struct sock *sk)
 {
        const struct tcp_sock *tp = tcp_sk(sk);
        struct htcp *ca = inet_csk_ca(sk);
-       ca->last_cong = ca->undo_last_cong;
+       ca->ccount = ca->undo_ccount;
        ca->maxRTT = ca->undo_maxRTT;
        ca->old_maxB = ca->undo_old_maxB;
        return max(tp->snd_cwnd, (tp->snd_ssthresh<<7)/ca->beta);
@@ -85,10 +77,10 @@ static inline void measure_rtt(struct sock *sk)
                ca->minRTT = srtt;
 
        /* max RTT */
-       if (icsk->icsk_ca_state == TCP_CA_Open && tp->snd_ssthresh < 0xFFFF && htcp_ccount(ca) > 3) {
+       if (icsk->icsk_ca_state == TCP_CA_Open && tp->snd_ssthresh < 0xFFFF && ca->ccount > 3) {
                if (ca->maxRTT < ca->minRTT)
                        ca->maxRTT = ca->minRTT;
-               if (ca->maxRTT < srtt && srtt <= ca->maxRTT+msecs_to_jiffies(20))
+               if (ca->maxRTT < srtt && srtt <= ca->maxRTT+HZ/50)
                        ca->maxRTT = srtt;
        }
 }
@@ -100,12 +92,6 @@ static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked)
        struct htcp *ca = inet_csk_ca(sk);
        u32 now = tcp_time_stamp;
 
-       if (icsk->icsk_ca_state == TCP_CA_Open)
-               ca->pkts_acked = pkts_acked;
-
-       if (!use_bandwidth_switch)
-               return;
-
        /* achieved throughput calculations */
        if (icsk->icsk_ca_state != TCP_CA_Open &&
            icsk->icsk_ca_state != TCP_CA_Disorder) {
@@ -120,7 +106,7 @@ static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked)
                        && now - ca->lasttime >= ca->minRTT
                        && ca->minRTT > 0) {
                __u32 cur_Bi = ca->packetcount*HZ/(now - ca->lasttime);
-               if (htcp_ccount(ca) <= 3) {
+               if (ca->ccount <= 3) {
                        /* just after backoff */
                        ca->minB = ca->maxB = ca->Bi = cur_Bi;
                } else {
@@ -149,7 +135,7 @@ static inline void htcp_beta_update(struct htcp *ca, u32 minRTT, u32 maxRTT)
                }
        }
 
-       if (ca->modeswitch && minRTT > msecs_to_jiffies(10) && maxRTT) {
+       if (ca->modeswitch && minRTT > max(HZ/100, 1) && maxRTT) {
                ca->beta = (minRTT<<7)/maxRTT;
                if (ca->beta < BETA_MIN)
                        ca->beta = BETA_MIN;
@@ -165,7 +151,7 @@ static inline void htcp_alpha_update(struct htcp *ca)
 {
        u32 minRTT = ca->minRTT;
        u32 factor = 1;
-       u32 diff = htcp_cong_time(ca);
+       u32 diff = ca->ccount * minRTT; /* time since last backoff */
 
        if (diff > HZ) {
                diff -= HZ;
@@ -230,21 +216,32 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt,
 
                measure_rtt(sk);
 
+               /* keep track of number of round-trip times since last backoff event */
+               if (ca->snd_cwnd_cnt2++ > tp->snd_cwnd) {
+                       ca->ccount++;
+                       ca->snd_cwnd_cnt2 = 0;
+                       htcp_alpha_update(ca);
+               }
+
                /* In dangerous area, increase slowly.
                 * In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd
                 */
-               if ((tp->snd_cwnd_cnt * ca->alpha)>>7 >= tp->snd_cwnd) {
+               if ((tp->snd_cwnd_cnt++ * ca->alpha)>>7 >= tp->snd_cwnd) {
                        if (tp->snd_cwnd < tp->snd_cwnd_clamp)
                                tp->snd_cwnd++;
                        tp->snd_cwnd_cnt = 0;
-                       htcp_alpha_update(ca);
-               } else
-                       tp->snd_cwnd_cnt += ca->pkts_acked;
-
-               ca->pkts_acked = 1;
+               }
        }
 }
 
+/* Lower bound on congestion window. */
+static u32 htcp_min_cwnd(struct sock *sk)
+{
+       const struct tcp_sock *tp = tcp_sk(sk);
+       return tp->snd_ssthresh;
+}
+
+
 static void htcp_init(struct sock *sk)
 {
        struct htcp *ca = inet_csk_ca(sk);
@@ -252,19 +249,11 @@ static void htcp_init(struct sock *sk)
        memset(ca, 0, sizeof(struct htcp));
        ca->alpha = ALPHA_BASE;
        ca->beta = BETA_MIN;
-       ca->pkts_acked = 1;
-       ca->last_cong = jiffies;
 }
 
 static void htcp_state(struct sock *sk, u8 new_state)
 {
        switch (new_state) {
-       case TCP_CA_Open:
-               {
-                       struct htcp *ca = inet_csk_ca(sk);
-                       ca->last_cong = jiffies;
-               }
-               break;
        case TCP_CA_CWR:
        case TCP_CA_Recovery:
        case TCP_CA_Loss:
@@ -276,6 +265,7 @@ static void htcp_state(struct sock *sk, u8 new_state)
 static struct tcp_congestion_ops htcp = {
        .init           = htcp_init,
        .ssthresh       = htcp_recalc_ssthresh,
+       .min_cwnd       = htcp_min_cwnd,
        .cong_avoid     = htcp_cong_avoid,
        .set_state      = htcp_state,
        .undo_cwnd      = htcp_cwnd_undo,
@@ -288,6 +278,8 @@ static int __init htcp_register(void)
 {
        BUG_ON(sizeof(struct htcp) > ICSK_CA_PRIV_SIZE);
        BUILD_BUG_ON(BETA_MIN >= BETA_MAX);
+       if (!use_bandwidth_switch)
+               htcp.pkts_acked = NULL;
        return tcp_register_congestion_control(&htcp);
 }