[TCP]: add tcp_slow_start helper
Stephen Hemminger [Fri, 11 Nov 2005 01:07:24 +0000 (17:07 -0800)]
Move all the code that does linear TCP slowstart to one
inline function to ease later patch to add ABC support.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tcp.h
net/ipv4/tcp_bic.c
net/ipv4/tcp_cong.c
net/ipv4/tcp_highspeed.c
net/ipv4/tcp_htcp.c
net/ipv4/tcp_scalable.c
net/ipv4/tcp_vegas.c

index 15bdbc6..54c3998 100644 (file)
@@ -765,6 +765,16 @@ static inline __u32 tcp_current_ssthresh(const struct sock *sk)
                            (tp->snd_cwnd >> 2)));
 }
 
+/*
+ * Linear increase during slow start
+ */
+static inline void tcp_slow_start(struct tcp_sock *tp)
+{
+       if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+               tp->snd_cwnd++;
+}
+
+
 static inline void tcp_sync_left_out(struct tcp_sock *tp)
 {
        if (tp->rx_opt.sack_ok &&
index 5af99b3..1d0cd86 100644 (file)
@@ -220,14 +220,12 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack,
        if (!tcp_is_cwnd_limited(sk, in_flight))
                return;
 
-       if (tp->snd_cwnd <= tp->snd_ssthresh) {
-               /* In "safe" area, increase. */
-               if (tp->snd_cwnd < tp->snd_cwnd_clamp)
-                       tp->snd_cwnd++;
-       } else {
+       if (tp->snd_cwnd <= tp->snd_ssthresh)
+               tcp_slow_start(tp);
+       else {
                bictcp_update(ca, tp->snd_cwnd);
 
-                /* In dangerous area, increase slowly.
+               /* In dangerous area, increase slowly.
                 * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd
                 */
                if (tp->snd_cwnd_cnt >= ca->cnt) {
index 0705b49..6d3e883 100644 (file)
@@ -189,12 +189,11 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 rtt, u32 in_flight,
        if (!tcp_is_cwnd_limited(sk, in_flight))
                return;
 
-        if (tp->snd_cwnd <= tp->snd_ssthresh) {
-                /* In "safe" area, increase. */
-               if (tp->snd_cwnd < tp->snd_cwnd_clamp)
-                       tp->snd_cwnd++;
-       } else {
-                /* In dangerous area, increase slowly.
+       /* In "safe" area, increase. */
+        if (tp->snd_cwnd <= tp->snd_ssthresh)
+               tcp_slow_start(tp);
+       else {
+               /* In dangerous area, increase slowly.
                 * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd
                 */
                if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
index 5e56ad3..82b3c18 100644 (file)
@@ -119,10 +119,9 @@ 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) {
-               if (tp->snd_cwnd < tp->snd_cwnd_clamp)
-                       tp->snd_cwnd++;
-       } else {
+       if (tp->snd_cwnd <= tp->snd_ssthresh)
+               tcp_slow_start(tp);
+       else {
                /* Update AIMD parameters */
                if (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd) {
                        while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd &&
index 404a326..3284cfb 100644 (file)
@@ -210,11 +210,10 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt,
        if (!tcp_is_cwnd_limited(sk, in_flight))
                return;
 
-        if (tp->snd_cwnd <= tp->snd_ssthresh) {
-                /* In "safe" area, increase. */
-               if (tp->snd_cwnd < tp->snd_cwnd_clamp)
-                       tp->snd_cwnd++;
-       } else {
+        if (tp->snd_cwnd <= tp->snd_ssthresh)
+               tcp_slow_start(tp);
+       else {
+
                measure_rtt(sk);
 
                /* keep track of number of round-trip times since last backoff event */
@@ -224,7 +223,7 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt,
                        htcp_alpha_update(ca);
                }
 
-                /* In dangerous area, increase slowly.
+               /* 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) {
index a2fd256..26d7486 100644 (file)
@@ -24,17 +24,16 @@ static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 rtt,
        if (!tcp_is_cwnd_limited(sk, in_flight))
                return;
 
-       if (tp->snd_cwnd <= tp->snd_ssthresh) {
-               tp->snd_cwnd++;
-       } else {
+       if (tp->snd_cwnd <= tp->snd_ssthresh)
+               tcp_slow_start(tp);
+       else {
                tp->snd_cwnd_cnt++;
                if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)){
-                       tp->snd_cwnd++;
+                       if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+                               tp->snd_cwnd++;
                        tp->snd_cwnd_cnt = 0;
                }
        }
-       tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp);
-       tp->snd_cwnd_stamp = tcp_time_stamp;
 }
 
 static u32 tcp_scalable_ssthresh(struct sock *sk)
index 93c5f92..4376814 100644 (file)
@@ -236,8 +236,7 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack,
                        /* We don't have enough RTT samples to do the Vegas
                         * calculation, so we'll behave like Reno.
                         */
-                       if (tp->snd_cwnd > tp->snd_ssthresh)
-                               tp->snd_cwnd++;
+                       tcp_reno_cong_avoid(sk, ack, seq_rtt, in_flight, cnt);
                } else {
                        u32 rtt, target_cwnd, diff;
 
@@ -275,7 +274,7 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack,
                         */
                        diff = (old_wnd << V_PARAM_SHIFT) - target_cwnd;
 
-                       if (tp->snd_cwnd < tp->snd_ssthresh) {
+                       if (tp->snd_cwnd <= tp->snd_ssthresh) {
                                /* Slow start.  */
                                if (diff > gamma) {
                                        /* Going too fast. Time to slow down
@@ -295,6 +294,7 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack,
                                                            V_PARAM_SHIFT)+1);
 
                                }
+                               tcp_slow_start(tp);
                        } else {
                                /* Congestion avoidance. */
                                u32 next_snd_cwnd;
@@ -327,37 +327,17 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack,
                                else if (next_snd_cwnd < tp->snd_cwnd)
                                        tp->snd_cwnd--;
                        }
-               }
 
-               /* Wipe the slate clean for the next RTT. */
-               vegas->cntRTT = 0;
-               vegas->minRTT = 0x7fffffff;
+                       if (tp->snd_cwnd < 2)
+                               tp->snd_cwnd = 2;
+                       else if (tp->snd_cwnd > tp->snd_cwnd_clamp)
+                               tp->snd_cwnd = tp->snd_cwnd_clamp;
+               }
        }
 
-       /* The following code is executed for every ack we receive,
-        * except for conditions checked in should_advance_cwnd()
-        * before the call to tcp_cong_avoid(). Mainly this means that
-        * we only execute this code if the ack actually acked some
-        * data.
-        */
-
-       /* If we are in slow start, increase our cwnd in response to this ACK.
-        * (If we are not in slow start then we are in congestion avoidance,
-        * and adjust our congestion window only once per RTT. See the code
-        * above.)
-        */
-       if (tp->snd_cwnd <= tp->snd_ssthresh)
-               tp->snd_cwnd++;
-
-       /* to keep cwnd from growing without bound */
-       tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp);
-
-       /* Make sure that we are never so timid as to reduce our cwnd below
-        * 2 MSS.
-        *
-        * Going below 2 MSS would risk huge delayed ACKs from our receiver.
-        */
-       tp->snd_cwnd = max(tp->snd_cwnd, 2U);
+       /* Wipe the slate clean for the next RTT. */
+       vegas->cntRTT = 0;
+       vegas->minRTT = 0x7fffffff;
 }
 
 /* Extract info for Tcp socket info provided via netlink. */