From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH 0/2] fixes to arp_notify for virtual machine migration use case Date: Sun, 23 May 2010 23:37:22 -0700 (PDT) Message-ID: <20100523.233722.232536798.davem@davemloft.net> References: <1273671554.7572.11190.camel@zakaz.uk.xensource.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, shemminger@linux-foundation.org, jeremy.fitzhardinge@citrix.com, stable@kernel.org To: Ian.Campbell@citrix.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:46372 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753851Ab0EXGhN (ORCPT ); Mon, 24 May 2010 02:37:13 -0400 In-Reply-To: <1273671554.7572.11190.camel@zakaz.uk.xensource.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Ian Campbell Date: Wed, 12 May 2010 14:39:14 +0100 > Ian Campbell (2): > arp_notify: generate broadcast ARP reply not request. > arp_notify: generate arp_notify event on NETDEV_CHANGE too I don't agree with these changes. For the first one, I think the documentation is just wrong and the code is what expresses the intent. The idea is not to spam the world with a broadcast, only interested parties. Patch #2 I have major issues with, carriers flapping occaisionally is very common. I have several interfaces which do this even on lightly loaded networks. Iff we decide to do something like this (big "if") it would need to be rate limited so that it doesn't trigger due to normal flapping. If you want your VM networking devices to trigger this event maybe the best thing to do is to create a special notification which allows us to prevent from doing this ARP notify for spurious physical network device carrier flaps.