From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [Bugme-new] [Bug 11316] New: severe performance regression for iptables nat routing Date: Thu, 14 Aug 2008 23:49:33 -0600 Message-ID: <1218779373.23510.25.camel@2710p.home> References: <1218726484.23510.20.camel@2710p.home> <20080815053548.GA6366@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: kaber@trash.net, davem@davemloft.net, akpm@linux-foundation.org, buytenh@marvell.com, netdev@vger.kernel.org, bugme-daemon@bugzilla.kernel.org To: Herbert Xu Return-path: Received: from g5t0008.atlanta.hp.com ([15.192.0.45]:5361 "EHLO g5t0008.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751113AbYHOFuP (ORCPT ); Fri, 15 Aug 2008 01:50:15 -0400 In-Reply-To: <20080815053548.GA6366@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, 2008-08-15 at 15:35 +1000, Herbert Xu wrote: > On Fri, Aug 15, 2008 at 02:44:26PM +1000, Herbert Xu wrote: > > > > Actually, I think know what's going on but a raw packet dump should > > confirm whether we're getting a partial checksum. > > Nevermind, I think I've found the problem. > > loopback: Drop obsolete ip_summed setting > > Now that the network stack can handle inbound packets with partial > checksums, we should no longer clobber the ip_summed field in the > loopback driver. This is because CHECKSUM_UNNECESSARY implies that > the checksum field is actually valid which is not true for loopback > packets since it's only partial (and thus complemented). > > This allows packets from lo to then be SNATed to an external source > while still preserving the checksum's validity. Nope, that doesn't fix it. NAT'd throughput remains about the same. Thanks, Alex -- Alex Williamson HP Open Source & Linux Org.