Very poor network performance

[stefeman]

Hey, I have very poor network performance for all VM's inside proxmox. However the host is able to get full speeds.

Host machine (OVH Proxmox 4.3 default install):

wget http://ovh.net/files/1Gio.dat
1Gio.dat 36%[======> ] 371.91M 84.1MB/s eta 9s

KVM VM (VirtIO) (Ubuntu 16.04 with no extra settings) Bridged with OVH Failover IP

wget http://ovh.net/files/1Gio.dat
1Gio.dat.2 3%[ ] 34.80M 3.15MB/s eta 3m 11s

There are no I/O issues or limits because in the above scenario nothing is running on the host and there are no other VM's even created.

How can I troubleshoot this and possibly get this fixed?

 

[udo]

Hi,
is this happens in both directions?
Try with iperf (vm to host and vice versa, host <-> outside, vm <-> outside).

I had a long time ago, that with special 10GB-NICs the tcp.onload must be disabled, otherwise the perfomance was low in one direction.

Check also the mtu on all nics.

Udo

 

[LnxBil]

Maybe same problems with OVH already discussed in the forums. Have you read all the other entries concerning OVH?

 

[stefeman]

Yes, this problem was outside my reach. It was in their new Warsaw DC network. This was solved by OVH network engineer without me needing to do anything.