From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH 11/13] bnx2x: Forbid LRO on when XEN is enabled Date: Mon, 19 Apr 2010 09:14:46 -0700 Message-ID: <20100419091446.39e2510c@nehalam> References: <1271602258.27235.200.camel@lb-tlvb-vladz> <1271603485.3679.210.camel@localhost> <20100418.205858.193699902.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: bhutchings@solarflare.com, vladz@broadcom.com, eilong@broadcom.com, netdev@vger.kernel.org, dmitry@broadcom.com To: David Miller Return-path: Received: from mail.vyatta.com ([76.74.103.46]:34224 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750891Ab0DSUOc (ORCPT ); Mon, 19 Apr 2010 16:14:32 -0400 In-Reply-To: <20100418.205858.193699902.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Sun, 18 Apr 2010 20:58:58 -0700 (PDT) David Miller wrote: > From: Ben Hutchings > Date: Sun, 18 Apr 2010 16:11:25 +0100 > > > On Sun, 2010-04-18 at 17:50 +0300, Vladislav Zolotarov wrote: > >> LRO cannot be used on virtualized environment, so it is best > >> to disable it on compile time in XEN kernel. > > [...] > > > > If you want to cripple your performance, I'm not going to stand in your > > way, but be aware that most distribution kernels now enable CONFIG_XEN. > > There is also zero reason to do this. > > When the XEN code or whatever setups up the bridge, LRO will be > disabled by the bridge code. > > It automatically issues ethtool LRO disable commands to the devices > involved in the bridge configuration. And it has done this for > a _long_ time. The ipv4 routing code will do the same. > > This change is bogus and likely based upon behavior in some ancient > distribution kernel that lacks the ethtool facilities. > > I absolutely refuse to apply this. Agreed. It is often devices that implement LRO, but don't have way to turn it off.