From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Fink Subject: Re: [net-next-2.6 PATCH 2/5] ixgbe: drop support for UDP in RSS hash generation Date: Tue, 20 Jul 2010 02:07:54 -0400 Message-ID: <20100720020754.135b5ff7.billfink@mindspring.com> References: <20100719235831.14112.14175.stgit@localhost.localdomain> <20100719235925.14112.65890.stgit@localhost.localdomain> <20100719.202417.218061462.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: jeffrey.t.kirsher@intel.com, netdev@vger.kernel.org, gospo@redhat.com, bphilips@novell.com, alexander.h.duyck@intel.com, donald.c.skidmore@intel.com To: David Miller Return-path: Received: from elasmtp-mealy.atl.sa.earthlink.net ([209.86.89.69]:56868 "EHLO elasmtp-mealy.atl.sa.earthlink.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932065Ab0GTGH5 (ORCPT ); Tue, 20 Jul 2010 02:07:57 -0400 In-Reply-To: <20100719.202417.218061462.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 19 Jul 2010, David Miller wrote: > From: Jeff Kirsher > Date: Mon, 19 Jul 2010 16:59:27 -0700 > > > From: Alexander Duyck > > > > This change removes UDP from the supported protocols for RSS hashing. The > > reason for removing this protocol is because IP fragmentation was causing a > > network flow to be broken into two streams, one for fragmented, and one for > > non-fragmented and this in turn was causing out-of-order issues. > > > > Signed-off-by: Alexander Duyck > > Acked-by: Don Skidmore > > Signed-off-by: Jeff Kirsher > > Applied. Should there be a /proc or ethtool setting for whether or not to use RSS hashing for UDP flows? I would think that for many common UDP applications, IP fragmentation would not be an issue because they often tend to use sub-MTU sized datagrams. And of course UDP does not guarantee in-order delivery in any event. Then a remaining issue is what the default setting of such an option should be. I would lean to having it enabled by default, but I can also see the safety argument for having it off by default. -Bill