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There is question about network between different server,but i got a different situation.

I have two VM in a server,and I tried to test maximum network speed between two VM.

OS : CentOS

VSwitch speed : 10Gb/s (1.25GB/s)

Virtual network adapter speed : 10Gb/s

VM used VSwitch and Virtual network adapter to communicate,and there is no ethernet cable to impact network speed.

VM A : nc -l 20000 > /dev/null

VM B : time dd if=/dev/zero bs=100M count=200 | nc <VM A> 20000

200+0 records in
200+0 records out
20971520000 bytes (21 GB) copied, 122.466 s, 171 MB/s

real    2m2.479s
user    0m2.148s
sys     3m10.841s

The above command is used to test only network speed(not include disk read and write)

There may some communicate overhead in network.

I thought the network speed should be 1 GB/s,but why the speed is so slow.

What factor impacts the network speed or how can i speedup my network?

Thanks in advanced.

  • Have you changed the network settings according to your other question on both machines? – Sven Nov 8 '18 at 9:07
  • @Sven yes,I already change to new virtual network adapter,so is now 10 Gb/s speed – kevin su Nov 8 '18 at 10:00

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