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authorLuca De Cicco <ldecicco@gmail.com>2006-06-11 23:02:19 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2006-06-17 21:30:38 -0700
commitbc726a71d2799f0f8b68a17f49d86aa030f64abc (patch)
treed16e9cc28069700c8f0a7cc8878ef04edab2206e /net/ipv4/tcp_westwood.c
parent[TCP] Westwood: bandwidth filter startup (diff)
downloadlinux-dev-bc726a71d2799f0f8b68a17f49d86aa030f64abc.tar.xz
linux-dev-bc726a71d2799f0f8b68a17f49d86aa030f64abc.zip
[TCP] Westwood: reset RTT min after FRTO
RTT_min is updated each time a timeout event occurs in order to cope with hard handovers in wireless scenarios such as UMTS. Signed-off-by: Luca De Cicco <ldecicco@gmail.com> Signed-off-by: Stephen Hemminger <shemminger@dxpl.pdx.osdl.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_westwood.c')
-rw-r--r--net/ipv4/tcp_westwood.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/net/ipv4/tcp_westwood.c b/net/ipv4/tcp_westwood.c
index edf2ee19a8ba..4247da1384bf 100644
--- a/net/ipv4/tcp_westwood.c
+++ b/net/ipv4/tcp_westwood.c
@@ -40,6 +40,7 @@ struct westwood {
u32 rtt;
u32 rtt_min; /* minimum observed RTT */
u8 first_ack; /* flag which infers that this is the first ack */
+ u8 reset_rtt_min; /* Reset RTT min to next RTT sample*/
};
@@ -67,6 +68,7 @@ static void tcp_westwood_init(struct sock *sk)
w->bw_est = 0;
w->accounted = 0;
w->cumul_ack = 0;
+ w->reset_rtt_min = 1;
w->rtt_min = w->rtt = TCP_WESTWOOD_INIT_RTT;
w->rtt_win_sx = tcp_time_stamp;
w->snd_una = tcp_sk(sk)->snd_una;
@@ -142,6 +144,16 @@ static void westwood_update_window(struct sock *sk)
}
}
+static inline void update_rtt_min(struct westwood *w)
+{
+ if (w->reset_rtt_min) {
+ w->rtt_min = w->rtt;
+ w->reset_rtt_min = 0;
+ } else
+ w->rtt_min = min(w->rtt, w->rtt_min);
+}
+
+
/*
* @westwood_fast_bw
* It is called when we are in fast path. In particular it is called when
@@ -157,7 +169,7 @@ static inline void westwood_fast_bw(struct sock *sk)
w->bk += tp->snd_una - w->snd_una;
w->snd_una = tp->snd_una;
- w->rtt_min = min(w->rtt, w->rtt_min);
+ update_rtt_min(w);
}
/*
@@ -226,12 +238,14 @@ static void tcp_westwood_event(struct sock *sk, enum tcp_ca_event event)
case CA_EVENT_FRTO:
tp->snd_ssthresh = tcp_westwood_bw_rttmin(sk);
+ /* Update RTT_min when next ack arrives */
+ w->reset_rtt_min = 1;
break;
case CA_EVENT_SLOW_ACK:
westwood_update_window(sk);
w->bk += westwood_acked_count(sk);
- w->rtt_min = min(w->rtt, w->rtt_min);
+ update_rtt_min(w);
break;
default: