From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751697AbZEEEqT (ORCPT ); Tue, 5 May 2009 00:46:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750965AbZEEEqG (ORCPT ); Tue, 5 May 2009 00:46:06 -0400 Received: from qw-out-2122.google.com ([74.125.92.27]:63487 "EHLO qw-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750891AbZEEEqD (ORCPT ); Tue, 5 May 2009 00:46:03 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=eZlNS230Ljtm3DTa6XIry4broa6BnmD9ugAwbg/9jjMpj3H9WnmN6Pi7f/YylaUQIz hb+7VgcTkP3gVNM76MD6C09d4WTn7WB0sMbgl4OkTJjodldKZt/UpWJRODdp2v4zTVPX BiU+Xv1z7TCKWZ4exxAMzneRylvVvy9CdzGGg= Message-ID: <49FFC489.6080402@gmail.com> Date: Mon, 04 May 2009 22:46:01 -0600 From: Robert Hancock User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Matthias Saou CC: linux-kernel@vger.kernel.org Subject: Re: Wrong network usage reported by /proc References: <20090504171408.3e13822c@python3.es.egwn.lan> In-Reply-To: <20090504171408.3e13822c@python3.es.egwn.lan> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Matthias Saou wrote: > Hi, > > I'm posting here as a last resort. I've got lots of heavily used RHEL5 > servers (2.6.18 based) that are reporting all sorts of impossible > network usage values through /proc, leading to unrealistic snmp/cacti > graphs where the outgoing bandwidth used it higher than the physical > interface's maximum speed. > > For some details and a test script which compares values from /proc > with values from tcpdump : > https://bugzilla.redhat.com/show_bug.cgi?id=489541 > > The values collected using tcpdump always seem realistic and match the > values seen on the remote network equipments. So my obvious conclusion > (but possibly wrong given my limited knowledge) is that something is > wrong in the kernel, since it's the one exposing the /proc interface. > > I've reproduced what seems to be the same problem on recent kernels, > including the 2.6.27.21-170.2.56.fc10.x86_64 I'm running right now. The > simple python script available here allows to see it quite easily : > https://www.redhat.com/archives/rhelv5-list/2009-February/msg00166.html > > * I run the script on my Workstation, I have an FTP server enabled > * I download a DVD ISO from a remote workstation : The values match > * I start ping floods from remote workstations : The values reported > by /proc are much higher than the ones reported by tcpdump. I used > "ping -s 500 -f myworkstation" from two remote workstations > > If there's anything flawed in my debugging, I'd love to have someone > point it out to me. TIA to anyone willing to have a look. > > Matthias > There may well be a bug in the kernel you're using, but you'd likely have more luck reporting a bug to Red Hat - the RHEL5 kernel is quite old and heavily patched and not many LKML people will likely be familiar with what RH may have done to it..