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); } - To unsubscribe from this list: send the line "unsubscribe git-commits-head" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html