From owner-freebsd-net@FreeBSD.ORG Mon Sep 25 15:57:06 2006 Return-Path: X-Original-To: net@FreeBSD.org Delivered-To: freebsd-net@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id ACA2416A412; Mon, 25 Sep 2006 15:57:06 +0000 (UTC) (envelope-from jmg@hydrogen.funkthat.com) Received: from hydrogen.funkthat.com (gate.funkthat.com [69.17.45.168]) by mx1.FreeBSD.org (Postfix) with ESMTP id 8A00543D5C; Mon, 25 Sep 2006 15:57:04 +0000 (GMT) (envelope-from jmg@hydrogen.funkthat.com) Received: from hydrogen.funkthat.com (r3g7vgsxq9i7sknu@localhost.funkthat.com [127.0.0.1]) by hydrogen.funkthat.com (8.13.6/8.13.3) with ESMTP id k8PFuw6g094553; Mon, 25 Sep 2006 08:56:59 -0700 (PDT) (envelope-from jmg@hydrogen.funkthat.com) Received: (from jmg@localhost) by hydrogen.funkthat.com (8.13.6/8.13.3/Submit) id k8PFuw1h094552; Mon, 25 Sep 2006 08:56:58 -0700 (PDT) (envelope-from jmg) Date: Mon, 25 Sep 2006 08:56:58 -0700 From: John-Mark Gurney To: Dan Nelson Message-ID: <20060925155658.GB80527@funkthat.com> Mail-Followup-To: Dan Nelson , current@FreeBSD.org, net@FreeBSD.org, Andre Oppermann , mohans@FreeBSD.org References: <20060925095745.GA80527@funkthat.com> <20060925154659.GE73717@dan.emsphone.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060925154659.GE73717@dan.emsphone.com> User-Agent: Mutt/1.4.2.1i X-Operating-System: FreeBSD 5.4-RELEASE-p6 i386 X-PGP-Fingerprint: B7 EC EF F8 AE ED A7 31 96 7A 22 B3 D8 56 36 F4 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html Cc: mohans@FreeBSD.org, Andre Oppermann , current@FreeBSD.org, net@FreeBSD.org Subject: Re: odd TCP rtt/retransmit timeout issue... X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: John-Mark Gurney List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 25 Sep 2006 15:57:06 -0000 Dan Nelson wrote this message on Mon, Sep 25, 2006 at 10:46 -0500: > In the last episode (Sep 25), John-Mark Gurney said: > > I was brining up another interface that I just added to /etc/rc.conf > > and ran the command /etc/rc.d/netif start to initalize it... But > > then my connection never came back.... I found that the shell was > > still active as I could type commands like sleep 5, and another > > session's w would see sleep 5 run on the session... even filling up > > the send-q w/ 32k of data didn't get the HEAD box to send any data to > > the client... > > > > With the help of silby, I managed to find that the t_rxtcur value in > > the tcpcb was getting a very large value. The session that hung had > > a retransmit timeout of 19 days... This led us to find that the > > TCPT_RANGESET macro was letting very large tvmin values override the > > more sane tvmax values due to an extra else. I have added that so we > > shouldn't see any more multi day timeouts, but we still apparently > > have a problem where the rtt value calculated is wildly incorrect... > > > > It appears that each connection will get a different "random" rtt > > values... From a few connections to my machine: > > (kgdb) print ((struct tcpcb *)0xc3a34af8)->t_rxtcur > > $3 = 64000 > > (kgdb) print ((struct tcpcb *)0xc3a3457c)->t_rxtcur > > $6 = 1662654093 > > (kgdb) print ((struct tcpcb *)0xc3a343a8)->t_rxtcur > > $12 = 1358 > > (kgdb) print ((struct tcpcb *)0xc3a9e1d4)->t_rxtcur > > $17 = 203 > > (kgdb) print ((struct tcpcb *)0xc3a9e000)->t_rxtcur > > $19 = 284155863 > > Do you have net.inet.tcp.inflight.enable=1 ? You might be hitting Yes. > something related to kern/75122. You'll want to pull the raw gnats > repository file to read it; the query-pr.cgi web interface doesn't > parse the file right and it loses all the replies. Doesn't look like it... I just disabled inflight, and my first connection got: (kgdb) print ((struct tcpcb *)0xc3a4857c)->t_rxtcur $1 = 921479340 -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."