From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: reminder, 2.6.18 window... Date: Wed, 24 May 2006 15:05:54 -0400 Message-ID: <4474AE92.3030501@garzik.org> References: <20060523.182217.59656237.davem@davemloft.net> <447412CA.50303@ipom.com> <4474A489.4080308@garzik.org> <20060524185644.GF22881@ipom.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:47497 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S1750779AbWEXTF6 (ORCPT ); Wed, 24 May 2006 15:05:58 -0400 To: Phil Dibowitz In-Reply-To: <20060524185644.GF22881@ipom.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Phil Dibowitz wrote: > On Wed, May 24, 2006 at 02:23:05PM -0400, Jeff Garzik wrote: >> I disagree that we should bother about clearing statistics. It always >> adds more complication than necessary. Few (if any) other statistics in >> Linux permit easy clearing, often because adding operations other than >> 'increment' or 'read' requires adding expensive spinlocks or atomic >> operations. > > Every networking device in the world supports clearing interface statistics. > Why should linux not be able to do the most basic operation on any > cisco/juniper/enterasys/whatever managed switch or router? > > It's a common operation on a network interface, I don't see why this is a > concern. > > When I'm debugging a networking issue On a cluster of hundreds and hundreds > of machines at work, I want to be able to reset them all quickly, and get a > rough idea of if they're all climbing, if they're all climbing at the same > rate, etc. And being able to do "for i in `cat hostlist`; do ssh $i ethtool -z > eth0; done" is really, really, REALLY, useful. Obtaining the difference between two numbers is not that difficult. Given any method of clearing statistics across your cluster, I'm certain you can come up with a similar method of obtaining the current statistic (the baseline). Jeff