From owner-freebsd-net@FreeBSD.ORG Mon Feb 11 11:18:15 2013 Return-Path: Delivered-To: net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 48AB0EB for ; Mon, 11 Feb 2013 11:18:15 +0000 (UTC) (envelope-from andre@freebsd.org) Received: from c00l3r.networx.ch (c00l3r.networx.ch [62.48.2.2]) by mx1.freebsd.org (Postfix) with ESMTP id 993B31E1B for ; Mon, 11 Feb 2013 11:18:14 +0000 (UTC) Received: (qmail 27029 invoked from network); 11 Feb 2013 12:36:05 -0000 Received: from c00l3r.networx.ch (HELO [127.0.0.1]) ([62.48.2.2]) (envelope-sender ) by c00l3r.networx.ch (qmail-ldap-1.03) with SMTP for ; 11 Feb 2013 12:36:05 -0000 Message-ID: <5118D375.5000501@freebsd.org> Date: Mon, 11 Feb 2013 12:18:13 +0100 From: Andre Oppermann User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130107 Thunderbird/17.0.2 MIME-Version: 1.0 To: Andrey Zonov Subject: Re: [PATCH] Add a new TCP_IGNOREIDLE socket option References: <201301221511.02496.jhb@freebsd.org> <50FF06AD.402@networx.ch> <061B4EA5-6A93-48A0-A269-C2C3A3C7E77C@lakerest.net> <201302060746.43736.jhb@freebsd.org> <511292C9.4040307@mu.org> <51166019.9040104@mu.org> <51177818.2090900@FreeBSD.org> In-Reply-To: <51177818.2090900@FreeBSD.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: net@freebsd.org, Alfred Perlstein , Randall Stewart , Kevin Oberman , John Baldwin X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 11 Feb 2013 11:18:15 -0000 On 10.02.2013 11:36, Andrey Zonov wrote: > On 2/10/13 9:05 AM, Kevin Oberman wrote: >> >> This is a subject rather near to my heart, having fought battles with >> congestion back in the dark days of Windows when it essentially >> defaulted to TCPIGNOREIDLE. It was a huge pain, but it was the only >> way Windows did TCP in the early days. It simply did not implement >> slow-start. This was really evil, but in the days when lots of links >> were 56K and T-1 was mostly used for network core links, the Internet, >> small as it was back then, did not melt, though it glowed a >> frightening shade of red fairly often. Today too many systems running >> like this would melt thins very quickly. >> > > Google made many many TCP tweaks. Increased initial window, small RTO, > enabled ignore after idle and others. They published that, other people > just blindly applied these tunings and the Internet still works. In general Google does provide quite a bit of data with their experiments showing that it isn't harmful and that it helps the case. Smaller RTO (1s) has become a RFC so there was very broad consensus in TCPM that is a good thing. We don't have it yet because we were not fully compliant in one case (loss of first segment). I've fixed that a while back and will bring 1s RTO soon to HEAD. I'm pretty sure that Google doesn't ignore idle on their Internet facing servers. They may have proposed a decay mechanism in the past. I'd have to check the TCPM archives for that. -- Andre