Network Performance issues in KVM Linux VM's

telemagic

New Member
Jan 20, 2013
18
2
1
Hi Guys

I have been doing some performance testing with my Proxmox test cluster.

I am performing iperf tests.

I am running on 3 x HP G5 Blade servers with 2 x 3.0ghz quad core Xeons and 16gb ram in each.

I am testing to another linux host on the blade centre, and all blades are connected to a gigabit cisco switch.

When I test from the host node to other server I get 900-950mbit a sec.
When I test from a linux container to the other server i get same 900-950mbit a sec.
When I test from a linux kvm VM I get 500-600mbit max.

Anyone got any ideas what is causing the bottleneck in the kvm?

Regards
 
Here are my iperf results, testing a Debian Wheezy VM with virtio network (hardware is an Intel Modular Server, 1 Gbit Network)

iperf between VM and host

Code:
root@wheezy-bench:~# iperf  -c 192.168.7.60
------------------------------------------------------------
Client connecting to 192.168.7.60, TCP port 5001
TCP window size: 23.5 KByte (default)
------------------------------------------------------------
[  3] local 192.168.7.230 port 47357 connected with 192.168.7.60 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  12.9 GBytes  11.1 Gbits/sec

iperf between VM and other host

Code:
root@wheezy-bench:~# iperf -c 192.168.7.62
------------------------------------------------------------
Client connecting to 192.168.7.62, TCP port 5001
TCP window size: 23.5 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.7.230 port 41133 connected with 192.168.7.62 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 1.10 GBytes 942 Mbits/sec

can´t be better! make sure you use virtio and a up2date kernel inside your VM
 
Hi

Thanks for the reply. I tried the same with virtip and got good results. Didnt get 11gbs per sec but I got 980odd mb per sec. I read somewhere that performance on virt is limited to the hardware of the network card in system?

But when I use the e1000 and not virt why do I seem to get only half duplex?

I have a squeeze based adsl bonding system that does not like the virtio driver.

Regards
 
Hi

Thanks for the reply. I tried the same with virtip and got good results. Didnt get 11gbs per sec but I got 980odd mb per sec. I read somewhere that performance on virt is limited to the hardware of the network card in system?

But when I use the e1000 and not virt why do I seem to get only half duplex?

I have a squeeze based adsl bonding system that does not like the virtio driver.

Regards

Hi, you need to use virtio card if you want good speed. (they use some feature to "bypass" the virtualisation layer).

What are your physical network card ? model ? speed ?(10GBE or 1GBE ).
 

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