From owner-freebsd-current@FreeBSD.ORG Sun Nov 4 20:41:18 2012 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 4C488C34; Sun, 4 Nov 2012 20:41:18 +0000 (UTC) (envelope-from andreast-list@fgznet.ch) Received: from smtp.fgznet.ch (mail.fgznet.ch [81.92.96.47]) by mx1.freebsd.org (Postfix) with ESMTP id E4A858FC0A; Sun, 4 Nov 2012 20:41:17 +0000 (UTC) Received: from deuterium.andreas.nets (dhclient-91-190-14-19.flashcable.ch [91.190.14.19]) by smtp.fgznet.ch (8.13.8/8.13.8/Submit_SMTPAUTH) with ESMTP id qA4KFQiE091552; Sun, 4 Nov 2012 21:15:27 +0100 (CET) (envelope-from andreast-list@fgznet.ch) Message-ID: <5096CCDE.7090305@fgznet.ch> Date: Sun, 04 Nov 2012 21:15:26 +0100 From: Andreas Tobler User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5; rv:16.0) Gecko/20121026 Thunderbird/16.0.2 MIME-Version: 1.0 To: Andre Oppermann Subject: Re: weird network problems on current since 10/28/2012 References: <201211031740.qA3HeqVX001622@pozo.com> <201211040113.qA41DfLn001577@pozo.com> <50964FBB.4010600@andric.com> <50967453.5090503@freebsd.org> In-Reply-To: <50967453.5090503@freebsd.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.64 on 81.92.96.47 Cc: Kim Culhan , Dimitry Andric , freebsd-current@freebsd.org, Adrian Chadd X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 04 Nov 2012 20:41:18 -0000 On 04.11.12 14:57, Andre Oppermann wrote: > On 04.11.2012 13:11, Kim Culhan wrote: >> On Sun, November 4, 2012 6:21 am, Dimitry Andric wrote: >>> On 2012-11-04 02:13, Manfred Antar wrote: >>>> At 03:29 PM 11/3/2012, Adrian Chadd wrote: >>>>> On 3 November 2012 10:40, Manfred Antar wrote: >>>>>> i have problem connecting to freebsd box on local network since last sunday. >>>>>> the last kernel that works: >>>>>> FreeBSD 10.0-CURRENT #0: Sun Oct 28 12:14:38 PDT 2012 >>>>>> anything after that, sometimes i can connect, other times just hangs. >>>>>> any network connection hangs ===== pop httpd ssh etc etc. >>>>>> anyone have any ideas ? >>>>>> i can checkout different sources and see if i can locate the changes that cause >>>>>> this. >>>>> >>>>> Please do! >>> ... >>>> Here is what I found doing : >>>> setenv CVSROOT /usr/home/ncvs >>>> >>>> cvs co -D"October 28, 2012 12:14:38 PDT" sys >>>> >>>> A kernel from that time works fine. >>>> >>>> doing: >>>> >>>> cvs up -D"October 28, 2012 13:14:38 PDT" sys 1 hour later >>>> the following files were changed: >>>> sys/netinet/tcp_input.c >>>> sys/netinet/tcp_timer.c >>>> sys/netinet/tcp_var.h >>>> >>>> Building a kernel from these new files is when the problem starts. >>> >>> So, your problems seem to have been introduced by this commit by Andre: >>> >>> http://svn.freebsd.org/changeset/base/242266 >>> >>> Increase the initial CWND to 10 segments as defined in IETF TCPM >>> draft-ietf-tcpm-initcwnd-05. It explains why the increased initial >>> window improves the overall performance of many web services without >>> risking congestion collapse. >>> >>> As long as it remains a draft it is placed under a sysctl marking it >>> as experimental: >>> net.inet.tcp.experimental.initcwnd10 = 1 >>> When it becomes an official RFC soon the sysctl will be changed to >>> the RFC number and moved to net.inet.tcp. >>> >>> This implementation differs from the RFC draft in that it is a bit >>> more conservative in the case of packet loss on SYN or SYN|ACK because >>> we haven't reduced the default RTO to 1 second yet. Also the restart >>> window isn't yet increased as allowed. Both will be adjusted with >>> upcoming changes. >>> >>> Is is enabled by default. In Linux it is enabled since kernel 3.0. >>> >>> After the commit, there was a small discussion thread on svn-src-head@ >>> about the possible problems with the approach. Maybe you are >>> experiencing those? >>> >>> As the commit message says, you should be able to turn the feature off >>> using: >>> >>> sysctl net.inet.tcp.experimental.initcwnd10=0 >>> >>> Can you please try that, and see if the problems go away? >> >> FWIW this did not make the problem go away on 2 machines. > > Yes, this very much looks like the same problem as in PR/173309. > > Please try the attached patch. It fixes the connection hang issue. > There may be a second issue I debugging currently base on the feedback > from Fabian Keil. I jump into this thread since I have a similar network issue. My scenario: 'make installkernel DESTDIR=/netboot/test' to a nfs mounted drive. The nfs drive on the server is an ufs fs. No zfs. Up to r242261 I can install the kernel (or world) in a fluent way to the nfs destination. >From r242262 it doesn't work smooth. I have stalls, sometimes my patience is not enough and I kill the process. I tried 242266 with the above mentioned patch. No real success. How can I help/test? TIA, Andreas