[OmniOS-discuss] Potential KVM Virtio Performance Issues

John Barfield john.barfield at bissinc.com
Tue Mar 24 21:34:47 UTC 2015

Okay found the problem. 

After further testing I achieved 952 MBytes on a VM-2-VM connection...1 
linux Ubuntu 12.04 vm to another CentOS 6.6 VM running on two different 
SmartOS host machines (through an extreme networks switch).

This was puzzling so I look at how joyent ran the VM’s command with 
pargs…I found that they do not use the following format:

-net nic,vlan=1,name=${VNIC2},model=virtio,macaddr=${mac2} \
-net vnic,vlan=1,name=${VNIC2},ifname=${VNIC2},macaddr=${mac2} \

They use this format:

-device \
8,vlan=0 \
-net \
vnic,name=${VNIC1},vlan=0,ifname=${VNIC1} \

I’m not sure if the txtimer values did anything performance gaining or 
not…I’m pretty sure just switching to the -device configuration instead of 
the legacy -net nic configuration is what did the trick. 

If anyone wants me to I’ll test and see if that was the only difference. 

Have a great day!

John Barfield / Sr Principal Engineer
+1 (214) 425-0783/ john.barfield at bissinc.com
BISS, Inc. Office: +1 (214) 506-8354 

4925 Greenville Ave Suite 900
Dallas, TX 75206
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On 3/24/15, 2:29 PM, "John Barfield" <john.barfield at bissinc.com> wrote:

>Greetings OmnisOS community! This is my first time to ask a question on 
>this list so here goes. I’ve deployed a zone on omnios and a KVM virtual 
>machine within the zone. I’ve been doing some initial virtio network 
>interface performance testing with iperf and the following are my results 
>(default out of the box for all moving parts). 
>OmniOS build stable: r151012
>Test Interfaces:
>GZ Phys = igb0
>KVM Vnic: kvm0 over igb0
>GZ Vnic: gvm0 over igb0
>Zone Vnic: zvm0 over igb0
>Network addressing: All vnics are with
>Zone Brand: Omni-ti ipkg
>Qemu-Kvm Guest: Centos 6.6 x86_64
>iPerf Results:
>KVM Guest -> Global Zone = 151 Mbytes (Expected close to 1 GByte)
>KVM Guest -> KVM Zone = 147 Mbytes (Expected close to 1 GByte)
>Zone -> Global Zone = 5.0GBytes (These were expected since it was a host 
>only VNIC network)
>GZ -> Zone = 4.7 Gbytes (These were expected since it was a host only 
>My question is are there any tweaks that I’m missing to get the full 
>performance potential within the guest? Why am I only seeing 147 Mbytes 
>between KVM and the hosting zone or the global zone? 
>I’m testing with an isolated network and vnics only, so the traffic is 
>never leaving the physical host to go over the wire.
>I do have cpu capped at 16 cores and memory capped at 16GB of memory in 
>the zone. Is there some default network capping that I’m missing? Or 
>process throttling?
>MTU is 1500 across the board. 
>I did the same test with etherstubs at first but though maybe I was 
>an MTU mismatch because I received the same 147 Mbyte result…however a 
>subsequent test using just the GZ -> child zone showed 5.0GBps over the 
>etherstub switch just like when I only used the VNIC’s over igb0.  
>Also just for grins I tested two bare metal hosts on my physical network 
>with iperf…one being CentOS 6.5 and the other OmniOS build r151012 and 
>received 1.09 Gbytes over a physical switch. 
>Your thoughts are appreciated!
>John Barfield / Sr Principal Engineer
>+1 (214) 425-0783/ john.barfield at bissinc.com
>BISS, Inc. Office: +1 (214) 506-8354 
>4925 Greenville Ave Suite 900
>Dallas, TX 75206
>support.bissinc.com <http://htmlsig.com/support.bissinc.com>
>OmniOS-discuss mailing list
>OmniOS-discuss at lists.omniti.com

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