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Date: Thu, 17 Nov 2016 01:31:12 +0000
From: "Zhangming (James, Euler)" <james.zhangming@...wei.com>
To: Jason Wang <jasowang@...hat.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC: "Michael S. Tsirkin" <mst@...hat.com>,
Vlad Yasevic <vyasevic@...hat.com>,
Amnon Ilan <ailan@...hat.com>
Subject: Re: Virtio_net support vxlan encapsulation package TSO offload
discuss
On 2016年11月15日 11:28, Jason Wang wrote:
>On 2016年11月10日 14:19, Zhangming (James, Euler) wrote:
>> On 2016年11月09日 15:14, Jason Wang wrote:
>>> 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
>> Thank you for your advice, I will start it right now.
>>
>> Thanks
>
>Cool, one more question: while at it, I think you may want to add support for dpdk too?
>
>Thanks
Do you mean that the patch should be compatible with virtio pmd, or give virtio pmd patch?
Thanks
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