From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Graf Subject: Re: update frequency for stats in /proc/net/dev Date: Tue, 18 Dec 2007 15:57:07 +0100 Message-ID: <20071218145707.GV11220@postel.suug.ch> References: <4767CD16.5050904@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org To: Mark Seger Return-path: Received: from postel.suug.ch ([194.88.212.233]:53829 "EHLO postel.suug.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756175AbXLRO4r (ORCPT ); Tue, 18 Dec 2007 09:56:47 -0500 Content-Disposition: inline In-Reply-To: <4767CD16.5050904@hp.com> Sender: netdev-owner@vger.kernel.org List-ID: * Mark Seger 2007-12-18 08:37 > Anyhow, I just wanted to let people know that ALL tools that monitor > once a second on older counters will get the wrong numbers and tools > that correct for the wrong number by using fractional intervals (and I > suspect mine is the only one that does) but run on newer kernels will > also get the wrong numbers. In any event, if anyone is interested in > trying out collectl - it monitors a LOT more than just networks - you > can snag a copy of from http://collectl.sourceforge.net/ if you'd like > to take if for a drive. The website has a lot of output examples to > give you a better idea what it can do. I even included a writeup about > the odd network performance observations at > http://collectl.sourceforge.net/NetworkStats.html I've solved this problem by using netlink to read the interface counters ten times per second and maintain an own counter from which I calculate the rate exactly once per second/minute/hour. The rate per second may still be inaccurate to some degree, therefore I keep a history of 2-5 rates and take them into account to smoothen the result. This works fairly well with _all_ operating systems.