Thread (44 messages) 44 messages, 10 authors, 2008-01-09

Re: [PATCH] tcp-illinois: incorrect beta usage

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!
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