how to check the connection speed for virtio_nic in Linux VM

[jagan]

Hi,

I have installed a Linux VM with virtio virtual nic. To check the network connection speed I have used ethtool, but the speed it is showing as unknown. When I change the interface model to E1000, the speed it is showing as 1000Mbps.

How do I check the network speed in Linux guest OS for virtio nic interface?

In windows VM in network properties, I can see the speed as 10Gbps for virtio nic and 1Gbps for E1000 nic.

 

[t.lamprecht]

Hi,

VirtIO has no real fixed speed/bandwidth, any value showing up for the device in the OS is rather "fake".

The virtual NIC is as fast as the system can copy out data from VM to the target, which means it's either limited by the network your Proxmox VE (VM host) is connected too, or the Memory speed if you transmit between VM and Proxmox VE host itself (at least if packets do not get routed out, due to network/address setup).

You can use iperf or iperf3 to get a rough estimate of what bandwidth is available between the VM and another device in the network, e.g., between VM and PVE host:

# on both (assuming VM is Debian-like)
apt install iperf

# on PVE: start server
iperf -s

# in VM: run test to server
# iperf -c IP-ADDRESS-OF-PVE-HOST

 

[lingguchong]

The speed of the 10G fiber optic network card used to connect to the LINUX VM through the iperf test is basically 10G, and the test of the WIN VM on the same node is 2-4G. How to adjust the configuration of the windows VM to make the network bandwidth normal?