Re: [PATCH] tcp-illinois: incorrect beta usage
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: 2007-11-29 14:23:37
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: 2007-11-29 14:23:37
On Wed, Nov 28, 2007 at 03:47:25PM -0800, Stephen Hemminger wrote:
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 <redacted>Applied to net-2.6. Thanks Stephen! -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} [off-list ref] Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt