Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a357dde9df33f28611e6a3d4f88265e39bcc8880
Commit: a357dde9df33f28611e6a3d4f88265e39bcc8880
Parent: 5e5234ff17ef98932688116025b30958bd28a940
Author: Stephen Hemminger <[EMAIL PROTECTED]>
AuthorDate: Fri Nov 30 01:10:55 2007 +1100
Committer: Herbert Xu <[EMAIL PROTECTED]>
CommitDate: Fri Nov 30 01:10:55 2007 +1100
[TCP] illinois: Incorrect beta usage
Lachlan Andrew observed that my TCP-Illinois implementation uses the
beta value incorrectly:
The parameter beta in the paper specifies the amount to decrease
*by*: that is, on loss,
W <- W - beta*W
but in tcp_illinois_ssthresh() uses beta as the amount
to decrease *to*: W <- beta*W
This bug makes the Linux TCP-Illinois get less-aggressive on uncongested
network,
hurting performance. Note: since the base beta value is .5, it has no
impact on a congested network.
Signed-off-by: Stephen Hemminger <[EMAIL PROTECTED]>
Signed-off-by: Herbert Xu <[EMAIL PROTECTED]>
---
net/ipv4/tcp_illinois.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/net/ipv4/tcp_illinois.c b/net/ipv4/tcp_illinois.c
index 64f1cba..5aa5f54 100644
--- a/net/ipv4/tcp_illinois.c
+++ b/net/ipv4/tcp_illinois.c
@@ -298,7 +298,7 @@ static u32 tcp_illinois_ssthresh(struct sock *sk)
struct illinois *ca = inet_csk_ca(sk);
/* Multiplicative decrease */
- return max((tp->snd_cwnd * ca->beta) >> BETA_SHIFT, 2U);
+ return max(tp->snd_cwnd - ((tp->snd_cwnd * ca->beta) >> BETA_SHIFT),
2U);
}
-
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