diff options
| author | Luca De Cicco <ldecicco@gmail.com> | 2006-06-11 23:02:19 -0700 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2006-06-17 21:30:38 -0700 |
| commit | bc726a71d2799f0f8b68a17f49d86aa030f64abc (patch) | |
| tree | d16e9cc28069700c8f0a7cc8878ef04edab2206e | |
| parent | b3a92eabe5b67bd207a38ae13dd51f4e08c1f6f7 (diff) | |
| download | linux-bc726a71d2799f0f8b68a17f49d86aa030f64abc.tar.bz2 | |
[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>
| -rw-r--r-- | net/ipv4/tcp_westwood.c | 18 |
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: |