Slow network speeds with virtio in guest linux kvm on PVE 2.3

[donty]

Hi all

We have a cluster of 3 hosts with raid 10 local disks and two iSCSI NAS boxes for lvm storage. Each host is 16GB or 32GB RAM, dual quad core 3GHz with two Intel NICs for the iscsi on separate Gb/s switches, all fine.

Each host has a third Broadcom Corporation NetXtreme II BCM5708 Gigabit Ethernet NIC on another dedicated 1Gb/s switch for network comms and each host is running fine at 1Gb/s tested via iperf between hosts.

Each KVM VM has virtio NIC but the performance using iperf or file copy to either the native host or a remote host is at best 100Mb/s. Current updates all applied and plenty of CPU and Memory available.

Current pveversion -v

pve-manager: 2.3-13 (pve-manager/2.3/7946f1f1)
running kernel: 2.6.32-19-pve
proxmox-ve-2.6.32: 2.3-95
pve-kernel-2.6.32-19-pve: 2.6.32-95
pve-kernel-2.6.32-18-pve: 2.6.32-88
lvm2: 2.02.95-1pve2
clvm: 2.02.95-1pve2
corosync-pve: 1.4.4-4
openais-pve: 1.1.4-2
libqb: 0.10.1-2
redhat-cluster-pve: 3.1.93-2
resource-agents-pve: 3.9.2-3
fence-agents-pve: 3.1.9-1
pve-cluster: 1.0-36
qemu-server: 2.3-20
pve-firmware: 1.0-21
libpve-common-perl: 1.0-49
libpve-access-control: 1.0-26
libpve-storage-perl: 2.3-7
vncterm: 1.0-4
vzctl: 4.0-1pve2
vzprocps: 2.0.11-2
vzquota: 3.1-1
pve-qemu-kvm: 1.4-10
ksm-control-daemon: 1.1-1

pveperf:

CPU BOGOMIPS: 37240.84
REGEX/SECOND: 834616
HD SIZE: 33.47 GB (/dev/mapper/pve-root)
BUFFERED READS: 157.73 MB/sec
AVERAGE SEEK TIME: 5.57 ms
FSYNCS/SECOND: 1353.40
DNS EXT: 12.02 ms
DNS INT: 0.70 ms



Any ideas of where to look? I would have thought that at least between host and vm it would be near wire speed.

Thanks!

 

[tom]

...
Any ideas of where to look? I would have thought that at least between host and vm it would be near wire speed.

Thanks!

yes, you can expect wire speed. provide more details about your KVM guest (qm config VMID).

 

[donty]

Thanks for getting back, here's the config for one of the KVM guests, it happens with most of them and with a variety of configs, this is exemplary:

bootdisk: virtio0
cores: 4
ide2: none,media=cdrom
memory: 6240
name: test.kvm
net0: virtio=9A:34:A4:31:2F:3B,bridge=vmbr0
onboot: 1
ostype: l26
sockets: 2
virtio0: LVM-ISCSI-SA-001:vm-112-disk-1,cache=writethrough,size=50G

 

[tom]

details about guest OS? full details please.

 

[donty]

Didnt get notice of a reply, sorry for the delay Tom.Example guest OSL: Debian 7.0 (Wheezy/Stable) 64bit using virtio drivers (also used Squeeze 64bit + virtio)Anything further you need?

 

[tom]

virtio drivers in wheezy should be fast, for squeeze you need to load a 3.2 kernel from squeeze-backports.

 

[donty]

Thanks Tom, I was not aware that virtio was not too good in Squeeze kernels - we have a mix of stuff, mainly debian bases eg Debs/Ubuntus etc but useful to know for any old appliances.I will upgrade the Squeeze installs and see what else I can find on Wheezy ones. It may just have been inopportune matching on iperf server/client ends that created Wheezy issues. Will note thread as solved if that was the case. Thanks again.

Oh well, cant see a Mark as Solved option in the forum tools anywhere so here is a foot note!