From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gabriel Barazer Subject: Re: [2.6.24.3][net] bug: TCP 3rd handshake abnormal timeouts Date: Sat, 15 Mar 2008 09:47:24 +0100 Message-ID: <47DB8D1C.7020006@oxeva.fr> References: <47DB28E9.4050309@oxeva.fr> <20080315065739.GL8953@1wt.eu> <20080315065849.GA11817@1wt.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, netdev@kernel.org To: Willy Tarreau Return-path: In-Reply-To: <20080315065849.GA11817@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hi Thanks for the netdev Cc, I didn't know where to write to the "network guys". By the way thanks for replying. It's hard to explain and describe a problem when you know people will ask you hundreds of questions related to application-level problems, or not reply because web/mysql problems are so common and generally not related to any kernel issue. On 03/15/2008 7:58:49 AM +0100, Willy Tarreau wrote: > > You should carefully check the the SYN-ACK received by the client has a > correct checksum ("cksum OK" in tcpdump output). It would be possible > that for some reason, something on the network randomly corrupts it. I used to use TCP offloading one time, and by the way never had a problem with it. Besides just to be sure, I have been able to reproduce the problem without any offload engine enabled (= not compiled into the kernel, mainly because it seems to hang the kernel at boot in 2.6.24.3). So I assume that is not the problem I use wireshark to analyse my pcap files and it says the checksum is correct on all packets. > Also, you say you have netfilter with conntrack. Is this on the client ? > If so, you should try disabling it to rule out any possible bug in the > connection tracking. I have the conntrack on both the client and server, and unfortunately can't disable it now on the client (I use it only for the REDIRECT target on a precise destination address and port, not MySQL related), however I will test today and disable it on the server, after I get some sleep (although I think the issue is on the client). Gabriel