10G链接的netcat和iperf结果存在巨大差异 [英] Huge difference in netcat and iperf results for a 10G link
问题描述
我很困惑看到netcat和iperf结果之间的巨大差异.我有10 G链接连接我的服务器和客户端.对于iperf，我的速度约为10Gb/s，对于netcat，速度仅为280 MB/s.可能是什么错误?
I am confused to see huge difference between netcat and iperf results. I am having 10 G link connecting my server and client. I am getting around 10Gb/s for iperf but only ~280 MB/s for netcat. What can be the error ?
对于Iperf
服务器
iperf -s
客户
iperf -c 172.79.56.27 -i1 -t 10
结果:
Client connecting to 172.79.56.27, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[ 3] local 172.79.56.28 port 46058 connected with 172.79.56.27 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0- 1.0 sec 1.07 GBytes 9.23 Gbits/sec
[ 3] 1.0- 2.0 sec 1.09 GBytes 9.35 Gbits/sec
[ 3] 2.0- 3.0 sec 1.09 GBytes 9.35 Gbits/sec
[ 3] 3.0- 4.0 sec 1.09 GBytes 9.35 Gbits/sec
[ 3] 4.0- 5.0 sec 1.09 GBytes 9.36 Gbits/sec
[ 3] 5.0- 6.0 sec 1.09 GBytes 9.35 Gbits/sec
[ 3] 6.0- 7.0 sec 1.09 GBytes 9.36 Gbits/sec
[ 3] 7.0- 8.0 sec 1.09 GBytes 9.35 Gbits/sec
[ 3] 8.0- 9.0 sec 1.09 GBytes 9.36 Gbits/sec
[ 3] 9.0-10.0 sec 1.09 GBytes 9.35 Gbits/sec
[ 3] 0.0-10.0 sec 10.9 GBytes 9.34 Gbits/sec
对于netcat，
服务器
nc -v -v -l -n 2222 >/dev/null
客户
time dd if=/dev/zero | nc -v -v -n 172.79.56.27 2222
Connection to 172.79.56.27 2222 port [tcp/*] succeeded!
^C6454690+0 records in
6454690+0 records out
3304801280 bytes (3.3 GB) copied, 11.4463 s, 289 MB/s
real 0m11.449s
user 0m6.868s
sys 0m15.372s
推荐答案
先生user1352179，
Mr user1352179,
再次运行netcat测试，然后在另一个窗口中查看htop.我敢打赌，您会看到这里的瓶颈是dd读/dev/zero的单线程.尝试再次与dd | netcat的'n'个实例并行运行测试，其中'n'=系统中的内核数.然后将所有并行运行的总带宽相加，以查看实际结果. (确保您在不同的端口上进行传输，并且使接收端也运行多个线程，并在多个端口上进行侦听).
Run your netcat test again and watch htop in another window. I bet you will see that the bottleneck here is the single thread of dd reading /dev/zero. Try running the test again in parallel with 'n' instances of dd|netcat where 'n' = the # of cores in your system. Then add the total bandwidth together from all parallel runs to see the real result. (Make sure you transmit on different ports & have your receiving end running multiple threads as well & listening on multiple ports).
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