Networking slow on proxmox host BUT fast inside VM

[el_floz]

Hi,

I have a bit of a strange issue whereby networking is about a quarter of the speed on the host machine (and in a container), compared with the speed inside a kvm on said host...?

If I download a test file from inside the qemu vm (with virtio network driver), I get pretty much linespeed with a wget of a test file (around 109 MB/s).

If I run the same test on the Proxmox host itself or inside an LXC container, it's about 25 MB/s...

All devices are using the same network interface / vmbr0, and all external factors are pretty much controlled.

Any pointers as to why that could be?

Thanks!

 

[Alwin]

Any pointers as to why that could be?

There's not much to go from, you need to provide more information, logs, configs, etc.

 

[el_floz]

I was more after general advice, in case this was a common thing to happen under certain conditions XYZ. Suspicions? Gut feeling?

My networking setup is simple, running a trusty Proliant with a handful of physical interfaces, but I only use one right now, and that is tied to vmbr0 (out of the box config). On subnet is being routed to that machine, and IP addresses from it are allocated to the Proxmox host itself, 2 VMs and on Container. As I said, speedy network in the VMs, but significantly (and very consistently) slower on the Proxmox host itself and inside the container.

The two VMs are Turnkey appliances, the container is a bog standard Debian 9, nothing fancy anywhere.

What should I provide more details on? Thanks!

 

[Alwin]

What should I provide more details on? Thanks!

Network config(s), container/VM configs, anything suspicious in syslog/journal, hardware details of the NIC/CPU. Anything else that might be related.

Virtualization has many layers and any of them could cause an effect, so it is hard to yell anything out of the dark.

 

[macklin]

Hi,

I have a bit of a strange issue whereby networking is about a quarter of the speed on the host machine (and in a container), compared with the speed inside a kvm on said host...?

If I download a test file from inside the qemu vm (with virtio network driver), I get pretty much linespeed with a wget of a test file (around 109 MB/s).

If I run the same test on the Proxmox host itself or inside an LXC container, it's about 25 MB/s...

All devices are using the same network interface / vmbr0, and all external factors are pretty much controlled.

Any pointers as to why that could be?

Thanks!

Hey - I know this is old but I'm wondering if you ever figured this out. I'm having the exact same problem. VM's are fine but LXC and host have slow network speeds.