VM showing 10Gbit NIC speed instead of 40Gbit

Swarm

New Member
Mar 8, 2023
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Hello all,

I recently bought a Mellanox ConnectX-4 EN MCX415A-BCAT NIC card, and installed it into my Proxmox machine. I can see it among the network devices, I can query it`s speed and it displays the expected value, which is 40Gbits. So everything looks, and works as I expect, but then I give this card to a vm, and it only shows up as a 10gb Nic.

My vm is a Windows server 2019 machine, and my host machine running on Proxmox 8.0.3.

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Enp133s0np0 is the only network port associated with the vmbr3 bridge.

1695632809214.png

I left the MTU size on the default value.

What am I missing?
 
Plase post your VM configuration tail -n +1 /etc/pve/qemu-server/<VMID>.conf
Regardless of what Windows is showing, do you experience any significant performance degradation inside the VM?
 
but then I give this card to a vm, and it only shows up as a 10gb Nic.
You don't give this network card a VM, you created a virtual NIC that attaches to the same bridge in which your 40 Gbit card is also attached. This NIC is showing 10 Gbit.
 
Plase post your VM configuration tail -n +1 /etc/pve/qemu-server/<VMID>.conf
Here is the output:
root@proxmox1:~# tail -n +1 /etc/pve/qemu-server/140.conf
agent: 1
boot: order=scsi0;ide2;ide0
cores: 4
cpu: x86-64-v2-AES
ide0: local:iso/virtio-win-0.1.229.iso,media=cdrom,size=522284K
ide2: local:iso/17763.3650.221105-1748.rs5_release_svc_refresh_SERVER_EVAL_x64FRE_en-us.iso,media=cdrom,size=5519618K
memory: 8192
meta: creation-qemu=8.0.2,ctime=1694586189
name: Win-Test
net0: virtio=32:41:15:CA:9D:BE,bridge=vmbr3,firewall=1
numa: 0
onboot: 1
ostype: l26
scsi0: local-zfs:vm-140-disk-0,iothread=1,size=32G
scsihw: virtio-scsi-single
smbios1: uuid=59cc3266-6f32-4869-8079-8d5affad79a7
sockets: 1
tags: rma
vmgenid: ef7d8b74-8aa0-41e8-a5be-e1b88b67196c

Regardless of what Windows is showing, do you experience any significant performance degradation inside the VM?
[/QUOTE]
Not really, but to be honest I didn`t really experimented with it.
I just did a quick iperf:
 

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