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Message-ID: <6db6b2a1-edbc-0068-d7d4-e8e15d18edc6@redhat.com>
Date: Tue, 15 Nov 2016 11:27:45 +0800
From: Jason Wang <jasowang@...hat.com>
To: "Zhangming (James, Euler)" <james.zhangming@...wei.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
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