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Date: Thu, 17 Nov 2016 15:10:42 -0800
From: Jarno Rajahalme <jarno.rajahalme@...il.com>
To: Jason Wang <jasowang@...hat.com>
Cc: "Zhangming (James, Euler)" <james.zhangming@...wei.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"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
I worked on the same issue a few months back. I rebased my proof-of-concept code to the current net-next and posted an RFC patch a moment ago.
I have zero experience on QEMU feature negotiation or extending the virtio_net spec. Since the virtio_net handling code is now all done using shared code, this should work for macvtap as well, not sure if macvtap needs some control plane changes.
I posted a separate patch to make af_packet also use the shared infra for virtio_net handling yesterday. My RFC patch assumes that af_packet need not be touched, i.e., assumes the af_packet patch is applied, even though the patches apply to net-next in either order.
Jarno
> On Nov 16, 2016, at 11:27 PM, Jason Wang <jasowang@...hat.com> wrote:
>
>
>
> On 2016年11月17日 09:31, Zhangming (James, Euler) wrote:
>> 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
>
> I mean it's better to prepare patches for both virtio pmd and dpdk.
>
> Thanks
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