From mboxrd@z Thu Jan 1 00:00:00 1970 From: Douglas Leith Subject: Re: Re the default linux tcp algorithm being changed from bic to cubic. Date: Thu, 28 Sep 2006 17:20:46 +0100 Message-ID: <451BF65E.9000701@nuim.ie> References: <451B9ED6.9090208@nuim.ie> <20060928071657.5d0cbf70@freekitty> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7BIT Cc: netdev , davem@davemloft.net Return-path: Received: from mail.nuim.ie ([149.157.1.19]:30187 "EHLO LARCH.MAY.IE") by vger.kernel.org with ESMTP id S1751921AbWI1QWV (ORCPT ); Thu, 28 Sep 2006 12:22:21 -0400 Received: from [192.168.0.2] ([212.2.174.101]) by NUIM.IE (PMDF V6.2-X17 #30789) with ESMTPA id <01M7QIRVM69A00WT0K@NUIM.IE> for netdev@vger.kernel.org; Thu, 28 Sep 2006 17:22:30 +0000 (GMT) In-reply-to: <20060928071657.5d0cbf70@freekitty> To: Stephen Hemminger Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Stephen Hemminger wrote: > On Thu, 28 Sep 2006 11:07:18 +0100 > Douglas Leith wrote: > >> Content-Type: text/plain; charset=UTF-8; format=flowed >> Content-Transfer-Encoding: 7bit >> >> Steve, >> >> I think we're all conscious of the fact that recent history contains >> quite a number of proposals for changes to tcp's congestion control >> algorithm for high bandwidth-delay product paths that on closer >> inspection have proved problematic in one way or another. It seems to >> be a hard problem to solve, so maybe that's fair enough and hopefully >> we'll end up with a workable solution soon. >> >> Where I'm coming from here though is that bic was made the linux default >> a year or so ago at a time when there were essentially no tests >> available on its performance other than the infocom paper by Injong. >> Subsequent tests have since highlighted a bunch of issues with bic. To >> my knowledge, we're currently in a similar situation with cubic as we >> were with bic back then i.e. essentially no independent tests >> investigating its behaviour. >> >> Of course I know Injong has posted some test results, but these are >> hardly independent as he's the author of both bic and cubic. Have there >> perhaps been private tests carried out (e.g. by osdl) ? If so, would it >> be possible to make them public ? If not, well that would be good to >> know too. > > My tests have been limited and showed no difference. It is worthy > of more discussion as to what is best. Could you rerun your tests? Unfortunately we haven't really looked at cubic at all to date as I didn't appreciate it was being seriously considered for the new default until Ian's post a few days ago. It'll take a little time to free up some bandwidth in people's time here, but we'd be happy to rerun the previous tests with cubic as a priority and generally try to have an initial poke around. Doug Hamilton Institute www.hamilton.ie