Network performance slows with multiple VMs

[skullitor13]

So I have a 10gb connections to my server and when I have 1 or 2 vms up and running I am getting close to that speed using iperf3. I noticed as I add my 3rd, 4th and 5th VM it starts to have a noticeable effect on the performance. it gets cut to about half. With all the VMs running I am only using about 40% of my CPU and 60% of the available ram.
I would expect a little drop off but 50% seems high.

The other odd thing is that when I run iperf3 to the host its self its getting the full 10gb speeds. Is having these multiple VMs on the same bridge slowing things down? is this to be expected? none of the VMs are network heavy VMs.

I have a Ryzen 2700X with 32GB of ram and a Chelsio t520 10 gig nic.

 

[Richard]

So I have a 10gb connections to my server and when I have 1 or 2 vms up and running I am getting close to that speed using iperf3. I noticed as I add my 3rd, 4th and 5th VM it starts to have a noticeable effect on the performance. it gets cut to about half. With all the VMs running I am only using about 40% of my CPU and 60% of the available ram.
I would expect a little drop off but 50% seems high.

The other odd thing is that when I run iperf3 to the host its self its getting the full 10gb speeds. Is having these multiple VMs on the same bridge slowing things down? is this to be expected? none of the VMs are network heavy VMs.

I have a Ryzen 2700X with 32GB of ram and a Chelsio t520 10 gig nic.

For better understanding it would be necessary to know the entire network configuration and how much resources the currently running VMs consume etc. (the easiest way to get this is running "pvereport") as well how (who is client, who server?) you ran iperf3.

Note that consuming 40% CPU is already a lot - try to use "lightweight" VMs leaving CPU usage < 10%.