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| author | Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> | 2007-02-21 23:02:30 -0800 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2007-04-25 22:23:04 -0700 |
| commit | 7487c48c4fd15d1e2542be1183b783562cfe10bc (patch) | |
| tree | 7939c5dfcfcbcc0b0984879a237518e7ff636a7f /net/ipv4 | |
| parent | 30935cf4f915c3178ce63331d6ff4c82163e26af (diff) | |
| download | linux-7487c48c4fd15d1e2542be1183b783562cfe10bc.tar.gz | |
[TCP] FRTO: Consecutive RTOs keep prior_ssthresh and ssthresh
In case a latency spike causes more than one RTO, the later should not cause the already reduced ssthresh to propagate into the prior_ssthresh since FRTO declares all such RTOs spurious at once or none of them. In treating of ssthresh, we mimic what tcp_enter_loss() does. The previous state (in frto_counter) must be available until we have checked it in tcp_enter_frto(), and also ACK information flag in process_frto(). Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/tcp_input.c | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 561e5d404988..194e880af51e 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1252,6 +1252,10 @@ int tcp_use_frto(const struct sock *sk) /* RTO occurred, but do not yet enter Loss state. Instead, defer RTO * recovery a bit and use heuristics in tcp_process_frto() to detect if * the RTO was spurious. + * + * Do like tcp_enter_loss() would; when RTO expires the second time it + * does: + * "Reduce ssthresh if it has not yet been made inside this window." */ void tcp_enter_frto(struct sock *sk) { @@ -1259,11 +1263,10 @@ void tcp_enter_frto(struct sock *sk) struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *skb; - tp->frto_counter = 1; - - if (icsk->icsk_ca_state <= TCP_CA_Disorder || + if ((!tp->frto_counter && icsk->icsk_ca_state <= TCP_CA_Disorder) || tp->snd_una == tp->high_seq || - (icsk->icsk_ca_state == TCP_CA_Loss && !icsk->icsk_retransmits)) { + ((icsk->icsk_ca_state == TCP_CA_Loss || tp->frto_counter) && + !icsk->icsk_retransmits)) { tp->prior_ssthresh = tcp_current_ssthresh(sk); tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk); tcp_ca_event(sk, CA_EVENT_FRTO); @@ -1285,6 +1288,7 @@ void tcp_enter_frto(struct sock *sk) tcp_set_ca_state(sk, TCP_CA_Open); tp->frto_highmark = tp->snd_nxt; + tp->frto_counter = 1; } /* Enter Loss state after F-RTO was applied. Dupack arrived after RTO, @@ -2513,12 +2517,16 @@ static void tcp_conservative_spur_to_response(struct tcp_sock *tp) * to prove that the RTO is indeed spurious. It transfers the control * from F-RTO to the conventional RTO recovery */ -static void tcp_process_frto(struct sock *sk, u32 prior_snd_una) +static void tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag) { struct tcp_sock *tp = tcp_sk(sk); tcp_sync_left_out(tp); + /* Duplicate the behavior from Loss state (fastretrans_alert) */ + if (flag&FLAG_DATA_ACKED) + inet_csk(sk)->icsk_retransmits = 0; + if (tp->snd_una == prior_snd_una || !before(tp->snd_una, tp->frto_highmark)) { tcp_enter_frto_loss(sk); @@ -2607,7 +2615,7 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag) flag |= tcp_clean_rtx_queue(sk, &seq_rtt); if (tp->frto_counter) - tcp_process_frto(sk, prior_snd_una); + tcp_process_frto(sk, prior_snd_una, flag); if (tcp_ack_is_dubious(sk, flag)) { /* Advance CWND, if state allows this. */ |