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[TCP]: add tcp_slow_start helper

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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>
This commit is contained in:
Stephen Hemminger
2005-11-10 17:07:24 -08:00
committed by David S. Miller
parent 2d2abbab63
commit 7faffa1c7f
7 changed files with 43 additions and 59 deletions
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42
net/ipv4/tcp_vegas.c
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@@ -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. */