From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: Virtio_net support vxlan encapsulation package TSO offload discuss Date: Wed, 9 Nov 2016 15:14:24 +0800 Message-ID: <53d0322b-4ce1-d0db-4b53-f9e860ece2c5@redhat.com> References: <3a0b8f10-f479-3ed5-dd10-5b92de3eb593@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Cc: "Michael S. Tsirkin" , Vlad Yasevic To: "Zhangming (James, Euler)" , "netdev@vger.kernel.org" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:50594 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751332AbcKIHOk (ORCPT ); Wed, 9 Nov 2016 02:14:40 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 2016年11月08日 19:58, Zhangming (James, Euler) wrote: > On 2016年11月08日 19:17, Jason Wang wrote: > >> On 2016年11月08日 19:13, Jason Wang wrote: >>> Cc Michael >>> >>> On 2016年11月08日 16:34, Zhangming (James, Euler) wrote: >>>> In container scenario, OVS is installed in the Virtual machine, and >>>> all the containers connected to the OVS will communicated through >>>> VXLAN encapsulation. >>>> >>>> By now, virtio_net does not support TSO offload for VXLAN >>>> encapsulated TSO package. In this condition, the performance is not >>>> good, sender is bottleneck >>>> >>>> I googled this scenario, but I didn’t find any information. Will >>>> virtio_net support VXLAN encapsulation package TSO offload later? >>>> >>> Yes and for both sender and receiver. >>> >>>> My idea is virtio_net open encapsulated TSO offload, and transport >>>> encapsulation info to TUN, TUN will parse the info and build skb with >>>> encapsulation info. >>>> >>>> OVS or kernel on the host should be modified to support this. Using >>>> this method, the TCP performance aremore than 2x as before. >>>> >>>> Any advice and suggestions for this idea or new idea will be greatly >>>> appreciated! >>>> >>>> Best regards, >>>> >>>> James zhang >>>> >>> Sounds very good. And we may also need features bits >>> (VIRTIO_NET_F_GUEST|HOST_GSO_X) for this. >>> >>> This is in fact one of items in networking todo list. (See >>> http://www.linux-kvm.org/page/NetworkingTodo). While at it, we'd >>> better support not only VXLAN but also other tunnels. >> Cc Vlad who is working on extending virtio-net headers. >> >>> We can start with the spec work, or if you've already had some bits >>> you can post them as RFC for early review. >>> >>> Thanks > Below is my demo code > Virtio_net.c > static int virtnet_probe(struct virtio_device *vdev), add belows codes: > if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF) || // avoid gso segment, it should be negotiation later, because in the demo I reuse num_buffers. > virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) { > dev->hw_enc_features |= NETIF_F_TSO; > dev->hw_enc_features |= NETIF_F_ALL_CSUM; > dev->hw_enc_features |= NETIF_F_GSO_UDP_TUNNEL; > dev->hw_enc_features |= NETIF_F_GSO_UDP_TUNNEL_CSUM; > dev->hw_enc_features |= NETIF_F_GSO_TUNNEL_REMCSUM; > > dev->features |= NETIF_F_GSO_UDP_TUNNEL; > dev->features |= NETIF_F_GSO_UDP_TUNNEL_CSUM; > dev->features |= NETIF_F_GSO_TUNNEL_REMCSUM; > } > > static int xmit_skb(struct send_queue *sq, struct sk_buff *skb), add below to pieces of codes > > if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL) > hdr->hdr.gso_type |= VIRTIO_NET_HDR_GSO_TUNNEL; > if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM) > hdr->hdr.gso_type |= VIRTIO_NET_HDR_GSO_TUNNEL_CSUM; > if (skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM) > hdr->hdr.gso_type |= VIRTIO_NET_HDR_GSO_TUNNEL_REMCSUM; > > if (skb->encapsulation && skb_is_gso(skb)) { > inner_mac_len = skb_inner_network_header(skb) - skb_inner_mac_header(skb); > tnl_len = skb_inner_mac_header(skb) - skb_mac_header(skb); > if ( !(inner_mac_len >> DATA_LEN_SHIFT) && !(tnl_len >> DATA_LEN_SHIFT) ) { > hdr->hdr.flags |= VIRTIO_NET_HDR_F_ENCAPSULATION; > hdr->num_buffers = (__virtio16)((inner_mac_len << DATA_LEN_SHIFT) | tnl_len); //we reuse num_buffers for simple , we should add extend member for later. > } else > hdr->num_buffers = 0; > } > > Tun.c > if (memcpy_fromiovecend((void *)&hdr, iv, offset, tun->vnet_hdr_sz)) //read header with negotiation length > return -EFAULT; > > if (hdr.gso_type & VIRTIO_NET_HDR_GSO_TUNNEL) //set tunnel gso info > skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL; > if (hdr.gso_type & VIRTIO_NET_HDR_GSO_TUNNEL_CSUM) > skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM; > if (hdr.gso_type & VIRTIO_NET_HDR_GSO_TUNNEL_REMCSUM) > skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM; > > if (hdr.flags & VIRTIO_NET_HDR_F_ENCAPSULATION) { //read tunnel info from header and set to built skb. > tnl_len = tun16_to_cpu(tun, hdr.num_buffers) & TUN_TNL_LEN_MASK; > payload_mac_len = tun16_to_cpu(tun, hdr.num_buffers) >> TUN_DATA_LEN_SHIFT; > mac_len = skb_network_header(skb) - skb_mac_header(skb); > skb_set_inner_mac_header(skb, tnl_len - mac_len); > skb_set_inner_network_header(skb, tnl_len + payload_mac_len - mac_len); > skb->encapsulation = 1; > } > > Something like this, and you probably need do something more: - use net-next.git to generate the patch (for the latest code) - add feature negotiation - tun/macvtap/qemu patches for this, you can start with tun/macvtap patches - support for all other SKB_GSO_* types which is not supported - use a new field instead of num_buffers - a virtio spec patch to describe the support for encapsulation offload Thanks