From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cong Wang Subject: Re: A performance regression of gretap Date: Thu, 11 Jul 2013 10:31:59 +0800 Message-ID: <1373509919.12250.6.camel@cr0> References: <327738182.1491147.1373450503005.JavaMail.root@redhat.com> <1373508910.12250.4.camel@cr0> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev To: Pravin Shelar Return-path: Received: from mx1.redhat.com ([209.132.183.28]:4732 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755063Ab3GKCcK (ORCPT ); Wed, 10 Jul 2013 22:32:10 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2013-07-10 at 19:28 -0700, Pravin Shelar wrote: > On Wed, Jul 10, 2013 at 7:15 PM, Cong Wang wrote: > > On Wed, 2013-07-10 at 06:01 -0400, Cong Wang wrote: > >> > >> Could you please take a look? And, gre tunnel is fine, this > >> problem only exists for gretap. I reviewed the gretap code, > >> but can't find any bug. > > > > After digging it a little bit, I found some of the packets on RX side > > have incorrect TCP checksum after going through gretap, while the > > packets captured on eth0 are all correct. > > > > Thanks. > > > I do not see it on my end. > Can you tell me NIC type and features set for eth device? Sure, it is virtio_net which is not able to do rx checksum, therefore ->ip_summed is CHECKSUM_NONE. # ethtool -i eth0 driver: virtio_net version: 1.0.0 firmware-version: bus-info: 0000:00:08.0 supports-statistics: no supports-test: no supports-eeprom-access: no supports-register-dump: no supports-priv-flags: no # ethtool -k eth0 Offload parameters for eth0: rx-checksumming: off tx-checksumming: on scatter-gather: on tcp-segmentation-offload: on udp-fragmentation-offload: on generic-segmentation-offload: on generic-receive-offload: on large-receive-offload: off rx-vlan-offload: off tx-vlan-offload: off ntuple-filters: off receive-hashing: off