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 13:22:35 -0400 Message-ID: <448EF45B.2080601@rtr.ca> References: <448EC6F3.3060002@rtr.ca> <448ECB09.3010308@rtr.ca> <448ED2FC.2040704@rtr.ca> <448ED9B3.8050506@rtr.ca> <448EEE9D.10105@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 , jheffner@psc.edu, davem@davemloft.net Return-path: Received: from rtr.ca ([64.26.128.89]:8358 "EHLO mail.rtr.ca") by vger.kernel.org with ESMTP id S932194AbWFMRWh (ORCPT ); Tue, 13 Jun 2006 13:22:37 -0400 To: Linux Kernel In-Reply-To: <448EEE9D.10105@rtr.ca> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Mark Lord wrote: > .. >> 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 ?? > Okay, here's the blob that broke it. > [TCP]: Set default max buffers from memory pool size > author John Heffner > Sat, 25 Mar 2006 09:34:07 +0000 (01:34 -0800) > committer David S. Miller > Sat, 25 Mar 2006 09:34:07 +0000 (01:34 -0800) > commit 7b4f4b5ebceab67ce440a61081a69f0265e17c2a > tree ac02c685ce23f2440fecbebaa5b55cd47947c03e tree > parent 2babf9daae4a3561f3264638a22ac7d0b14a6f52 commit | commitdiff > [TCP]: Set default max buffers from memory pool size > > This patch sets the maximum TCP buffer sizes (available to automatic > buffer tuning, not to setsockopt) based on the TCP memory pool size. > The maximum sndbuf and rcvbuf each will be up to 4 MB, but no more > than 1/128 of the memory pressure threshold. > > Signed-off-by: John Heffner > Signed-off-by: David S. Miller John / David: Any ideas on what's gone awry here?