Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=05bb1fad1cde025a864a90cfeb98dcbefe78a44a
Commit: 05bb1fad1cde025a864a90cfeb98dcbefe78a44a
Parent: 378be2c08314fc46e3f814fa264ff8ebdb79712f
Author: David S. Miller <[EMAIL PROTECTED]>
AuthorDate: Thu Aug 30 22:10:28 2007 -0700
Committer: David S. Miller <[EMAIL PROTECTED]>
CommitDate: Thu Aug 30 22:10:28 2007 -0700
[TCP]: Allow minimum RTO to be configurable via routing metrics.
Cell phone networks do link layer retransmissions and other
things that cause unnecessary timeout retransmits. So allow
the minimum RTO to be inflated per-route to deal with this.
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
---
include/linux/rtnetlink.h | 2 ++
net/ipv4/tcp_input.c | 14 ++++++++++++--
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index c91476c..dff3192 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -351,6 +351,8 @@ enum
#define RTAX_INITCWND RTAX_INITCWND
RTAX_FEATURES,
#define RTAX_FEATURES RTAX_FEATURES
+ RTAX_RTO_MIN,
+#define RTAX_RTO_MIN RTAX_RTO_MIN
__RTAX_MAX
};
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9785df3..1ee7212 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -555,6 +555,16 @@ static void tcp_event_data_recv(struct sock *sk, struct
sk_buff *skb)
tcp_grow_window(sk, skb);
}
+static u32 tcp_rto_min(struct sock *sk)
+{
+ struct dst_entry *dst = __sk_dst_get(sk);
+ u32 rto_min = TCP_RTO_MIN;
+
+ if (dst_metric_locked(dst, RTAX_RTO_MIN))
+ rto_min = dst->metrics[RTAX_RTO_MIN-1];
+ return rto_min;
+}
+
/* Called to compute a smoothed rtt estimate. The data fed to this
* routine either comes from timestamps, or from segments that were
* known _not_ to have been retransmitted [see Karn/Partridge
@@ -616,13 +626,13 @@ static void tcp_rtt_estimator(struct sock *sk, const
__u32 mrtt)
if (tp->mdev_max < tp->rttvar)
tp->rttvar -= (tp->rttvar-tp->mdev_max)>>2;
tp->rtt_seq = tp->snd_nxt;
- tp->mdev_max = TCP_RTO_MIN;
+ tp->mdev_max = tcp_rto_min(sk);
}
} else {
/* no previous measure. */
tp->srtt = m<<3; /* take the measured time to be rtt */
tp->mdev = m<<1; /* make sure rto = 3*rtt */
- tp->mdev_max = tp->rttvar = max(tp->mdev, TCP_RTO_MIN);
+ tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk));
tp->rtt_seq = tp->snd_nxt;
}
}
-
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