From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mc34.lon.server.colt.net (mc34.lon.server.colt.net [212.74.77.114]) by dpdk.org (Postfix) with SMTP id B91A85907 for ; Wed, 3 Sep 2014 16:08:20 +0200 (CEST) Received: from mc34.lon.server.colt.net (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5CD801A80DF for ; Wed, 3 Sep 2014 14:12:57 +0000 (UTC) Received: from mx3.qosmos.com (unknown [195.68.92.43]) by mc34.lon.server.colt.net (Postfix) with ESMTP id 409AD1A80DA for ; Wed, 3 Sep 2014 14:12:57 +0000 (UTC) X-IronPort-AV: E=Sophos;i="5.04,457,1406584800"; d="scan'208";a="1215461" Received: from unknown (HELO cercis.foret) ([10.10.2.42]) by mx3.qosmos.com with ESMTP; 03 Sep 2014 16:12:56 +0200 Message-ID: <540721E8.2010307@qosmos.com> Date: Wed, 03 Sep 2014 16:12:56 +0200 From: Franck Baudin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 MIME-Version: 1.0 To: "Xie, Huawei" , "Gray, Mark D" , Thomas Monjalon References: <1686757.iSdNo6aMGt@xps13> <738D45BC1F695740A983F43CFE1B7EA92D72308F@IRSMSX102.ger.corp.intel.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-MML: No X-TM-AS-Product-Ver: IMSVA-8.2.0.1679-7.5.0.1018-20926.005 X-TM-AS-Result: No--12.495-5.0-31-10 X-imss-scan-details: No--12.495-5.0-31-10 X-TM-AS-User-Approved-Sender: No X-TMASE-Version: IMSVA-8.2.0.1679-7.5.1018-20926.005 X-TMASE-Result: 10--12.495400-5.000000 X-TMASE-MatchedRID: RsPxVIkBekwtjw5zGtj91Ca1MaKuob8PC/ExpXrHizw76rqmQGSwT/ea 4uH4Y9hvWmBhIF8UJjOvWrz46u6NvagQOuSjPsjI9UVHiwLx0/Lv6kiVCTIVSh+ZGcvxEG4Eriu 1vXYzMu3Ewh+FBAsuQdYqEHZrK4jXZvjinbSBPqFN3UUbIf4esiseSAhqf1rRAryv4ykUqLvi8r DiR1RMiMCzDTSJRy9CzWG6/aKyjXIVnLoTgKrjJnGBmLio+mJgloU71ctjXZQ3Z3efQH+wj0G4y 8B4mD3lcex+cBH+RjeM58OQgF489I9oUcx9VMLgOX/V8P8ail1ZDL1gLmoa/PoA9r2LThYYKrau Xd3MZDVau/Gkfjk+cCgis7kmgcwR2gwW2oPIWw4eSZkag5aOyE7wSyZ+V/G6 Cc: "dev@dpdk.org" , "dpdk-ovs@lists.01.org" Subject: Re: [dpdk-dev] Wrong TCP checksum of packets sent by Linux guest (virtIO/vhost) X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Sep 2014 14:08:20 -0000 Hi, On 09/03/14 13:13, Xie, Huawei wrote: > Looping in the dpdk-ovs list. > > * Does the new vhost API allow a user to know if all the relevant offloads have > been > turned on/off for that interface? It seems that this is possible through the > virtio_net > structure but it would be good to get some feedback from the relevant person > working on DPDK (Huawei?). > > * If this is the case, then it is probably in the realm of the vswitch do the actual > checksum (for VM-VM) or correctly configure the NIC when sending out through > the physical interface. > > Comments? > > Mark: > So far not supported. This is important as well in VxLan case. For the packet flow > Guest A-> virtio -> ..->OVDK->.. -> Guest B. > 1) If guest A and B are on different host machines, say A and B respectively, and if the nic on A supports > vxlan checksum offload, then both guest and host needn't generate checksum, the nic will > generate checksum for both inner and outer packet. > 2) In VM2VM case, as it is trusted communication channel, could we negotiate with the guest tcp stack not to verify checksum > for received packet? The problem is that any TCP packet send by a vanilla Linux guest through vhost is incorrect (VM to anything, including other colocalied VMs). In other words, the VM cannot use TCP. QEMU options and ethtool -K csum off tso off ("TCP stack negociation") have no effect, maybe because the vhost backend is misbehaving. Franck