[ovs-dev] 答复: [PATCH v5] Use TPACKET_V3 to accelerate veth for userspace datapath

[=?gb2312?B?WWkgWWFuZyAo0e6gRCkt1Ma3/s7xvK/NxQ==?=]

In the same environment, but I used tap but not veth, retr number is 0 for
the case without this patch (of course, I applied Flavio's tap enable patch)

vagrant at ubuntu1804:~$ sudo ./run-iperf3.sh
Connecting to host 10.15.1.3, port 5201
[  4] local 10.15.1.2 port 54572 connected to 10.15.1.3 port 5201
[ ID] Interval           Transfer     Bandwidth       Retr  Cwnd
[  4]   0.00-10.00  sec  12.6 GBytes  10.9 Gbits/sec    0   3.14 MBytes
[  4]  10.00-20.00  sec  12.8 GBytes  11.0 Gbits/sec    0   3.14 MBytes
[  4]  20.00-30.00  sec  10.2 GBytes  8.76 Gbits/sec    0   3.14 MBytes
[  4]  30.00-40.00  sec  10.0 GBytes  8.63 Gbits/sec    0   3.14 MBytes
[  4]  40.00-50.00  sec  10.4 GBytes  8.94 Gbits/sec    0   3.14 MBytes
[  4]  50.00-60.00  sec  10.8 GBytes  9.31 Gbits/sec    0   3.14 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-60.00  sec  67.0 GBytes  9.59 Gbits/sec    0             sender
[  4]   0.00-60.00  sec  67.0 GBytes  9.59 Gbits/sec
receiver

Server output:
Accepted connection from 10.15.1.2, port 54570
[  5] local 10.15.1.3 port 5201 connected to 10.15.1.2 port 54572
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-10.00  sec  12.6 GBytes  10.9 Gbits/sec
[  5]  10.00-20.00  sec  12.8 GBytes  11.0 Gbits/sec
[  5]  20.00-30.00  sec  10.2 GBytes  8.76 Gbits/sec
[  5]  30.00-40.00  sec  10.0 GBytes  8.63 Gbits/sec
[  5]  40.00-50.00  sec  10.4 GBytes  8.94 Gbits/sec
[  5]  50.00-60.00  sec  10.8 GBytes  9.31 Gbits/sec
[  5]  60.00-60.00  sec  1.75 MBytes  9.25 Gbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-60.00  sec  0.00 Bytes  0.00 bits/sec                  sender
[  5]   0.00-60.00  sec  67.0 GBytes  9.59 Gbits/sec
receiver


iperf Done.
vagrant at ubuntu1804:~$

-----邮件原件-----
发件人: dev [mailto:ovs-dev-bounces at openvswitch.org] 代表 William Tu
发送时间: 2020年2月26日 6:32
收件人: yang_y_yi at 126.com
抄送: yang_y_yi <yang_y_yi at 163.com>; ovs-dev <ovs-dev at openvswitch.org>
主题: Re: [ovs-dev] [PATCH v5] Use TPACKET_V3 to accelerate veth for
userspace datapath

On Mon, Feb 24, 2020 at 5:01 AM <yang_y_yi at 126.com> wrote:
>
> From: Yi Yang <yangyi01 at inspur.com>
>
> We can avoid high system call overhead by using TPACKET_V3 and using 
> DPDK-like poll to receive and send packets (Note: send still needs to 
> call sendto to trigger final packet transmission).
>
> From Linux kernel 3.10 on, TPACKET_V3 has been supported, so all the 
> Linux kernels current OVS supports can run
> TPACKET_V3 without any problem.
>
> I can see about 30% performance improvement for veth compared to last 
> recvmmsg optimization if I use TPACKET_V3, it is about 1.98 Gbps, but 
> it was 1.47 Gbps before.
>
> TPACKET_V3 can support TSO, it can work only if your kernel can 
> support, this has been verified on Ubuntu 18.04 5.3.0-40-generic , if 
> you find the performance is very poor, please turn off tso for veth 
> interfces in case userspace-tso-enable is set to true.

Do you test the performance of enabling TSO?

Using veth (like your run-iperf3.sh) and with kernel 5.3.
Without your patch, with TSO enabled, I can get around 6Gbps But with this
patch, with TSO enabled, the performance drops to 1.9Gbps.

Regards,
William
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