[TCP]: add tcp_slow_start helper
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>
diff --git a/net/ipv4/tcp_vegas.c b/net/ipv4/tcp_vegas.c
index 93c5f92..4376814 100644
--- a/net/ipv4/tcp_vegas.c
+++ b/net/ipv4/tcp_vegas.c
@@ -236,8 +236,7 @@
/* 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 @@
*/
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 @@
V_PARAM_SHIFT)+1);
}
+ tcp_slow_start(tp);
} else {
/* Congestion avoidance. */
u32 next_snd_cwnd;
@@ -327,37 +327,17 @@
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. */