Re: [RFC Optimizing veth xsk performance 00/10]

[Jesper Dangaard Brouer <hawk@kernel.org>]

On 03/08/2023 16.04, huangjie.albert wrote:
> AF_XDP is a kernel bypass technology that can greatly improve performance.
> However, for virtual devices like veth, even with the use of AF_XDP sockets,
> there are still many additional software paths that consume CPU resources.
> This patch series focuses on optimizing the performance of AF_XDP sockets
> for veth virtual devices. Patches 1 to 4 mainly involve preparatory work.
> Patch 5 introduces tx queue and tx napi for packet transmission, while
> patch 9 primarily implements zero-copy, and patch 10 adds support for
> batch sending of IPv4 UDP packets. These optimizations significantly reduce
> the software path and support checksum offload.
> 
> I tested those feature with
> A typical topology is shown below:
> veth<-->veth-peer                                    veth1-peer<--->veth1
> 	1       |                                                  |   7
> 	        |2                                                6|
> 	        |                                                  |
> 	      bridge<------->eth0(mlnx5)- switch -eth1(mlnx5)<--->bridge1
>                    3                    4                 5
>               (machine1)                              (machine2)
> AF_XDP socket is attach to veth and veth1. and send packets to physical NIC(eth0)
> veth:(172.17.0.2/24)
> bridge:(172.17.0.1/24)
> eth0:(192.168.156.66/24)
> 
> eth1(172.17.0.2/24)
> bridge1:(172.17.0.1/24)
> eth0:(192.168.156.88/24)
> 
> after set default route、snat、dnat. we can have a tests
> to get the performance results.
> 
> packets send from veth to veth1:
> af_xdp test tool:
> link:https://github.com/cclinuxer/libxudp
> send:(veth)
> ./objs/xudpperf send --dst 192.168.156.88:6002 -l 1300
> recv:(veth1)
> ./objs/xudpperf recv --src 172.17.0.2:6002
> 
> udp test tool:iperf3
> send:(veth)
> iperf3 -c 192.168.156.88 -p 6002 -l 1300 -b 60G -u
> recv:(veth1)
> iperf3 -s -p 6002
> 
> performance:
> performance:(test weth libxdp lib)
> UDP                              : 250 Kpps (with 100% cpu)
> AF_XDP   no  zerocopy + no batch : 480 Kpps (with ksoftirqd 100% cpu)
> AF_XDP  with zerocopy + no batch : 540 Kpps (with ksoftirqd 100% cpu)
> AF_XDP  with  batch  +  zerocopy : 1.5 Mpps (with ksoftirqd 15% cpu)
> 
> With af_xdp batch, the libxdp user-space program reaches a bottleneck.

Do you mean libxdp [1] or libxudp ?

[1] https://github.com/xdp-project/xdp-tools/tree/master/lib/libxdp

> Therefore, the softirq did not reach the limit.
> 
> This is just an RFC patch series, and some code details still need
> further consideration. Please review this proposal.
>

I find this performance work interesting as we have customer requests
(via Maryam (cc)) to improve AF_XDP performance both native and on veth.

Our benchmark is stored at:
  https://github.com/maryamtahhan/veth-benchmark

Great to see other companies also interested in this area.

--Jesper

> thanks!
> 
> huangjie.albert (10):
>    veth: Implement ethtool's get_ringparam() callback
>    xsk: add dma_check_skip for  skipping dma check
>    veth: add support for send queue
>    xsk: add xsk_tx_completed_addr function
>    veth: use send queue tx napi to xmit xsk tx desc
>    veth: add ndo_xsk_wakeup callback for veth
>    sk_buff: add destructor_arg_xsk_pool for zero copy
>    xdp: add xdp_mem_type MEM_TYPE_XSK_BUFF_POOL_TX
>    veth: support zero copy for af xdp
>    veth: af_xdp tx batch support for ipv4 udp
> 
>   drivers/net/veth.c          | 729 +++++++++++++++++++++++++++++++++++-
>   include/linux/skbuff.h      |   1 +
>   include/net/xdp.h           |   1 +
>   include/net/xdp_sock_drv.h  |   1 +
>   include/net/xsk_buff_pool.h |   1 +
>   net/xdp/xsk.c               |   6 +
>   net/xdp/xsk_buff_pool.c     |   3 +-
>   net/xdp/xsk_queue.h         |  11 +
>   8 files changed, 751 insertions(+), 2 deletions(-)
>