From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH] TCP Veno module for kernel 2.6.16.13 Date: Thu, 25 May 2006 13:50:11 -0700 Message-ID: <20060525135011.470dc3dd@localhost.localdomain> References: <20060525.132350.39157903.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: ZHOU0022@ntu.edu.sg, baruch@ev-en.org, jmorris@namei.org, netdev@vger.kernel.org Return-path: Received: from smtp.osdl.org ([65.172.181.4]:46547 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1030407AbWEYUuX (ORCPT ); Thu, 25 May 2006 16:50:23 -0400 To: David Miller In-Reply-To: <20060525.132350.39157903.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, 25 May 2006 13:23:50 -0700 (PDT) David Miller wrote: > From: "#ZHOU BIN#" > Date: Thu, 25 May 2006 16:30:48 +0800 > > > Yes, I agree. Actually the main contribution of TCP Veno is not in > > this AI phase. No matter the ABC is added or not, TCP Veno can > > always improve the performance over wireless networks, according to > > our tests. > > It seems to me that the wireless issue is seperate from congestion > control. > > The key is to identify "true loss" due to overflow of intermediate > router queues, vs. "false loss" which is due to temporary radio > signal interference. Is it really possible to tell the two apart. Also, a lot of times when an access point is overloaded, performance is killed because of congestion overload. > This determination is a job for the loss detection in the generic ACK > processing code in tcp_input.c, not for a congestion control algorithm. > The congestion control algorithm uses the "true loss" information to > make congestion control decisions. > > We already have code that tries to make this differentiation, in the > form of FRTO, and your techniques can likely be placed there as well. The general idea of resetting cwnd to an estimate of capacity seems to be a general feature of Westwood, Veno, Compound and Africa. Also FreeBSD does the same thing, but they don't have a cool name.