On Fri, 21 Dec 2007, David Miller wrote:
> When Gavin respins the patch I'll look at in the context of submitting
> it as a bug fix. So Gavin please generate the patch against Linus's
> vanilla GIT tree or net-2.6, your choise.
The existing patch was against Linus' linux-2.6.git from a few days ago so
I've updated my tree and regenerated the patch (below). Is that the right
one?
I'm just checking through the existing CA modules. I don't see the rtt
used for RTO anywhere. This is what I gather they're each using rtt for.
tcp_highspeed.c doesn't implement .pkts_acked
tcp_hybla.c doesn't implement .pkts_acked
tcp_scalable.c doesn't implement .pkts_acked
tcp_bic.c ignores rtt value from .pkts_acked
tcp_lp.c seems to ignore rtt value from .pkts_acked (despite setting
TCP_CONG_RTT_STAMP for high res rtts -- why?)
tcp_vegas.c uses high res rtt to measure congestion signal, increase,
backoff -- TCP_CONG_RTT_STAMP set so doesn't use seq_rtt
tcp_veno.c uses high res rtt to measure congestion signal, increase,
backoff -- TCP_CONG_RTT_STAMP set so doesn't use seq_rtt
tcp_yeah.c uses high res rtt to measure congestion signal, increase,
backoff -- TCP_CONG_RTT_STAMP set so doesn't use seq_rtt
tcp_illinois.c uses rtt to scale increase, backoff
-- TCP_CONG_RTT_STAMP set so doesn't use seq_rtt
tcp_htcp.c uses rtt to scale increase, backoff
tcp_cubic.c uses rtt to scale increase, backoff
tcp_westwood.c scales backoff using rtt
So as far as I can tell, timeout stuff is not ever altered using
pkts_acked() so I guess this fix only affects westwood, htcp and cubic just
now.
I need to re-read properly, but I think the same problem affects the
microsecond values where TCP_CONG_RTT_STAMP is set (used by vegas, veno,
yeah, illinois). I might follow up with another patch which changes the
behaviour where TCP_CONG_RTT_STAMP when I'm more sure of that.
Thanks,
Gavin
Signed-off-by: Gavin McCullagh <[EMAIL PROTECTED]>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 889c893..6fb7989 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2651,6 +2651,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, s32
*seq_rtt_p,
u32 cnt = 0;
u32 reord = tp->packets_out;
s32 seq_rtt = -1;
+ s32 ca_seq_rtt = -1;
ktime_t last_ackt = net_invalid_timestamp();
while ((skb = tcp_write_queue_head(sk)) && skb != tcp_send_head(sk)) {
@@ -2686,13 +2687,15 @@ static int tcp_clean_rtx_queue(struct sock *sk, s32
*seq_rtt_p,
if (sacked & TCPCB_SACKED_RETRANS)
tp->retrans_out -= packets_acked;
flag |= FLAG_RETRANS_DATA_ACKED;
+ ca_seq_rtt = -1;
seq_rtt = -1;
if ((flag & FLAG_DATA_ACKED) ||
(packets_acked > 1))
flag |= FLAG_NONHEAD_RETRANS_ACKED;
} else {
+ ca_seq_rtt = now - scb->when;
if (seq_rtt < 0) {
- seq_rtt = now - scb->when;
+ seq_rtt = ca_seq_rtt;
if (fully_acked)
last_ackt = skb->tstamp;
}
@@ -2709,8 +2712,9 @@ static int tcp_clean_rtx_queue(struct sock *sk, s32
*seq_rtt_p,
!before(end_seq, tp->snd_up))
tp->urg_mode = 0;
} else {
+ ca_seq_rtt = now - scb->when;
if (seq_rtt < 0) {
- seq_rtt = now - scb->when;
+ seq_rtt = ca_seq_rtt;
if (fully_acked)
last_ackt = skb->tstamp;
}
@@ -2772,8 +2776,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, s32
*seq_rtt_p,
net_invalid_timestamp()))
rtt_us =
ktime_us_delta(ktime_get_real(),
last_ackt);
- else if (seq_rtt > 0)
- rtt_us = jiffies_to_usecs(seq_rtt);
+ else if (ca_seq_rtt > 0)
+ rtt_us = jiffies_to_usecs(ca_seq_rtt);
}
ca_ops->pkts_acked(sk, pkts_acked, rtt_us);
--
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