From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: 2.6.17: networking bug?? Date: Tue, 13 Jun 2006 12:58:05 -0400 Message-ID: <448EEE9D.10105@rtr.ca> References: <448EC6F3.3060002@rtr.ca> <448ECB09.3010308@rtr.ca> <448ED2FC.2040704@rtr.ca> <448ED9B3.8050506@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, Linus Torvalds Return-path: Received: from rtr.ca ([64.26.128.89]:17897 "EHLO mail.rtr.ca") by vger.kernel.org with ESMTP id S932188AbWFMQ6H (ORCPT ); Tue, 13 Jun 2006 12:58:07 -0400 To: Linux Kernel In-Reply-To: <448ED9B3.8050506@rtr.ca> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org .. > The site www.everymac.com is still not browseable until > setting /proc/sys/net/ipv4/tcp_window_scaling===0. > > There's one other difference I see in the tcpdump traces. > The first packets from each trace below show different > values for "wscale". The old (working) kernels use "wscale 2", > whereas 2.6.17 uses "wscale 6". In both cases, the value > seen in /proc/sys/net/ipv4/tcp_adv_win_scale is 2. Okay. More progress here. The calculation of the "wscale" values is based on the "tcp_rmem" sysctl numbers. The defaults for these *differ* between 2.6.16.18 and 2.6.17-rc*. 2.6.16: 4096 87380 174760 2.6.17: 4096 87380 2097152 If I change the tcp_rmem setting on 2.6.17 to match the old value, then the website www.everymac.com becomes accessible again: echo 4096 87380 174760 > /proc/sys/net/ipv4/tcp_rmem Looking at diffs between 2.6.16 and 2.6.17, I see a big rework of the tcp_rmem code in linux/net/ipv4/tcp.c Looks like something got broken there, or possibly the wscale calculations have a bug that is only triggered by the new rmem values ??