# Re: \[PATCH net-next v2 0/7\] virtio-net support xdp socket zero copy xmit

- From: Jason Wang \<hidden\>
- Date: 2021-01-18 06:30:57 
- List: netdev
- Page: https://ratatoskr.run/netdev/2021/01/7756762
- Thread: https://ratatoskr.run/netdev/2021/01/6223975/t.md

```text

On 2021/1/16 上午10:59, Xuan Zhuo wrote:
> XDP socket is an excellent by pass kernel network transmission framework. The
> zero copy feature of xsk (XDP socket) needs to be supported by the driver. The
> performance of zero copy is very good. mlx5 and intel ixgbe already support this
> feature, This patch set allows virtio-net to support xsk's zerocopy xmit
> feature.
>
> And xsk's zerocopy rx has made major changes to virtio-net, and I hope to submit
> it after this patch set are received.
>
> Compared with other drivers, virtio-net does not directly obtain the dma
> address, so I first obtain the xsk page, and then pass the page to virtio.
>
> When recycling the sent packets, we have to distinguish between skb and xdp.
> Now we have to distinguish between skb, xdp, xsk. So the second patch solves
> this problem first.
>
> The last four patches are used to support xsk zerocopy in virtio-net:
>
>   1. support xsk enable/disable
>   2. realize the function of xsk packet sending
>   3. implement xsk wakeup callback
>   4. set xsk completed when packet sent done
>
>
> ---------------- Performance Testing ------------
>
> The udp package tool implemented by the interface of xsk vs sockperf(kernel udp)
> for performance testing:
>
> xsk zero copy in virtio-net:
> CPU        PPS         MSGSIZE
> 28.7%      3833857     64
> 38.5%      3689491     512
> 38.9%      2787096     1456


Some questions on the results:

1) What's the setup on the vhost?
2) What's the setup of the mitigation in both host and guest?
3) Any analyze on the possible bottleneck via perf or other tools?

Thanks


>
> xsk without zero copy in virtio-net:
> CPU        PPS         MSGSIZE
> 100%       1916747     64
> 100%       1775988     512
> 100%       1440054     1456
>
> sockperf:
> CPU        PPS         MSGSIZE
> 100%       713274      64
> 100%       701024      512
> 100%       695832      1456
>
> Xuan Zhuo (7):
>    xsk: support get page for drv
>    virtio-net, xsk: distinguish XDP_TX and XSK XMIT ctx
>    xsk, virtio-net: prepare for support xsk zerocopy xmit
>    virtio-net, xsk: support xsk enable/disable
>    virtio-net, xsk: realize the function of xsk packet sending
>    virtio-net, xsk: implement xsk wakeup callback
>    virtio-net, xsk: set xsk completed when packet sent done
>
>   drivers/net/virtio_net.c    | 559 +++++++++++++++++++++++++++++++++++++++-----
>   include/linux/netdevice.h   |   1 +
>   include/net/xdp_sock_drv.h  |  10 +
>   include/net/xsk_buff_pool.h |   1 +
>   net/xdp/xsk_buff_pool.c     |  10 +-
>   5 files changed, 523 insertions(+), 58 deletions(-)
>
> --
> 1.8.3.1
>

```