From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: 2.6.20.7 TCP cubic (and bic) initial slow start way too slow? Date: Tue, 12 Jun 2007 17:16:03 -0700 Message-ID: <20070612171603.47736395@localhost> References: <20070512120739.371ada4f.billfink@mindspring.com> <649aecc70705120945q58ae79c9r8ff2dc5557658d1e@mail.gmail.com> <20070516024409.53049682.billfink@mindspring.com> <20070612.151258.120619253.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: billfink@mindspring.com, sangtae.ha@gmail.com, rhee@eos.ncsu.edu, rhee@ncsu.edu, netdev@vger.kernel.org To: David Miller Return-path: Received: from smtp2.linux-foundation.org ([207.189.120.14]:49456 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752146AbXFMAQb (ORCPT ); Tue, 12 Jun 2007 20:16:31 -0400 In-Reply-To: <20070612.151258.120619253.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, 12 Jun 2007 15:12:58 -0700 (PDT) David Miller wrote: > From: Bill Fink > Date: Wed, 16 May 2007 02:44:09 -0400 > > > [root@lang2 ~]# netstat -s | grep -i retrans > > 25446 segments retransmited > > 20936 fast retransmits > > 4503 retransmits in slow start > > 4 sack retransmits failed > > > > It then only took 2.14 seconds to transfer 1 GB of data. > > > > That's all for now. > > Thanks for all of your testing and numbers Bill. > > Inhong et al., we have to do something about this, the issue > has been known and sitting around for weeks if not months. > > How safely can we set the default initial_ssthresh to zero in > Cubic and BIC? Yes. set it to zero. The module parameter could even go, and just leave the route metric as a way to set/remember it.