[ovs-dev] 答复: iperf tcp issue on veth using afxdp

[Yi Yang (杨燚)-云服务集团]

Hi, Yifeng

I'll try it again. By the way, did you try af_packet for veth in OVS DPDK? In my machine it can reach 4Gbps, do you think af_xdp can reach this number?

-----邮件原件-----
发件人: Yifeng Sun [mailto:pkusunyifeng at gmail.com] 
发送时间: 2019年12月21日 9:11
收件人: William Tu <u9012063 at gmail.com>
抄送: <dev at openvswitch.org> <dev at openvswitch.org>; Ilya Maximets <i.maximets at ovn.org>; Eelco Chaudron <echaudro at redhat.com>; Yi Yang (杨燚)-云服务集团 <yangyi01 at inspur.com>
主题: Re: [ovs-dev] iperf tcp issue on veth using afxdp

This seems to be related to netdev-afxdp's batch size bigger than kernel's xdp batch size.
I created a patch to fix it.

https://patchwork.ozlabs.org/patch/1214397/

Could anyone take a look at this patch?

Thanks,
Yifeng

On Fri, Nov 22, 2019 at 9:52 AM William Tu <u9012063 at gmail.com> wrote:
>
> Hi Ilya and Eelco,
>
> Yiyang reports very poor TCP performance on his setup and I can also 
> reproduce it on my machine. Somehow I think this might be a kernel 
> issue, but I don't know where to debug this. Need your suggestion 
> about how to debug.
>
> So the setup is like the system-traffic, creating 2 namespaces and 
> veth devices and attach to OVS. I do remember to turn off tx offload 
> and ping, UDP, nc (tcp-mode) works fine.
>
> TCP using iperf drops to 0Mbps after 4 seconds.
> At server side:
> root at osboxes:~/ovs# ip netns exec at_ns0 iperf -s
> ------------------------------------------------------------
> Server listening on TCP port 5001
> TCP window size:  128 KByte (default)
> ------------------------------------------------------------
> [  4] local 10.1.1.1 port 5001 connected with 10.1.1.2 port 40384 
> Waiting for server threads to complete. Interrupt again to force quit.
>
> At client side
> root at osboxes:~/bpf-next# ip netns exec at_ns1 iperf -c 10.1.1.1 -i 1 
> -t 10
> ------------------------------------------------------------
> Client connecting to 10.1.1.1, TCP port 5001 TCP window size: 85.0 
> KByte (default)
> ------------------------------------------------------------
> [  3] local 10.1.1.2 port 40384 connected with 10.1.1.1 port 5001
> [ ID] Interval       Transfer     Bandwidth
> [  3]  0.0- 1.0 sec  17.0 MBytes   143 Mbits/sec
> [  3]  1.0- 2.0 sec  9.62 MBytes  80.7 Mbits/sec [  3]  2.0- 3.0 sec  
> 6.75 MBytes  56.6 Mbits/sec [  3]  3.0- 4.0 sec  11.0 MBytes  92.3 
> Mbits/sec [  3]  5.0- 6.0 sec  0.00 Bytes  0.00 bits/sec [  3]  6.0- 
> 7.0 sec  0.00 Bytes  0.00 bits/sec [  3]  7.0- 8.0 sec  0.00 Bytes  
> 0.00 bits/sec [  3]  8.0- 9.0 sec  0.00 Bytes  0.00 bits/sec [  3]  
> 9.0-10.0 sec  0.00 Bytes  0.00 bits/sec [  3] 10.0-11.0 sec  0.00 
> Bytes  0.00 bits/sec
>
> (after this, even ping stops working)
>
> Script to reproduce
> -------------------------
> ovs-vsctl -- add-br br0 -- set Bridge br0 datapath_type=netdev
>
> ip netns add at_ns0
> ip link add p0 type veth peer name afxdp-p0 ip link set p0 netns 
> at_ns0 ip link set dev afxdp-p0 up ovs-vsctl add-port br0 afxdp-p0
>
> ovs-vsctl -- set interface afxdp-p0 options:n_rxq=1 type="afxdp"
> options:xdp-mode=native
> ip netns exec at_ns0 sh << NS_EXEC_HEREDOC ip addr add "10.1.1.1/24" 
> dev p0 ip link set dev p0 up NS_EXEC_HEREDOC
>
> ip netns add at_ns1
> ip link add p1 type veth peer name afxdp-p1 ip link set p1 netns 
> at_ns1 ip link set dev afxdp-p1 up ovs-vsctl add-port br0 afxdp-p1 -- 
> \
>                set interface afxdp-p1 options:n_rxq=1 type="afxdp"
> options:xdp-mode=native
>
> ip netns exec at_ns1 sh << NS_EXEC_HEREDOC ip addr add "10.1.1.2/24" 
> dev p1 ip link set dev p1 up NS_EXEC_HEREDOC
>
> ethtool -K afxdp-p0 tx off
> ethtool -K afxdp-p1 tx off
> ip netns exec at_ns0 ethtool -K p0 tx off ip netns exec at_ns1 ethtool 
> -K p1 tx off
>
> ip netns exec at_ns0 ping  -c 10 -i .2 10.1.1.2 echo "ip netns exec 
> at_ns1 iperf -c 10.1.1.1 -i 1 -t 10"
> ip netns exec at_ns0 iperf -s
>
> Thank you
> William
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