From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [RFC] TCP limited slow start Date: Mon, 5 Jun 2006 10:17:10 -0700 Message-ID: <20060605101710.762c0351@dxpl.pdx.osdl.net> References: <20060602161312.3cb2ea66@localhost.localdomain> <20060602185403.1549e3c6@localhost.localdomain> <4481BD01.9020906@psc.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org Return-path: Received: from smtp.osdl.org ([65.172.181.4]:15814 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1751222AbWFERR0 (ORCPT ); Mon, 5 Jun 2006 13:17:26 -0400 To: John Heffner In-Reply-To: <4481BD01.9020906@psc.edu> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Sat, 03 Jun 2006 12:46:57 -0400 John Heffner wrote: > Stephen Hemminger wrote: > > Rolled my sleeve's up and gave this a try... > > > > This is a implementation of Sally Floyd's Limited Slow Start > > for Large Congestion Windows. > > Limited slow start is useful as a work-around for bottleneck queues that > are inappropriately short. I don't think it's good to run it all the > time by default (with a max_ssthresh < infinity), because it slows down > flows on healthy paths, and introduces another non-scalable parameter to > TCP. > > I see it as potentially useful as a per-route parameter, where you set > it deliberately to work around some known problematic path. A sysctl > with a default value of infinity might be okay as well. > > Practically speaking, we've had this in the Web100 patch for a long time > (and still do, look for WAD_MaxSsthresh), but I've never found it all > that useful. If the bottleneck queue is too short, you usually end up > getting screwed other ways too. > > -John I moved it off to tcp_highspeed.c only. That is seems appropriate because that is where you put the related RFC.