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List:       openvswitch-discuss
Subject:    [ovs-discuss] poor performance after adding vlan tag to a vport
From:       hkang.sunysb () gmail ! com (Hui Kang)
Date:       2014-04-30 16:12:53
Message-ID: CAPd85sLELMdHe6mZ_VBTgvj_Gq5hUMNXOrfHvcuxH8T5=a_5aA () mail ! gmail ! com
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Hi, Eugene,
I am using KVM. I set the vlan tag on the OVS bridge by

"ovs-vsctl set port vnet1 tag=1  # vnet1 is the vport for a VM"

So inside the VM, you actually can not see the vlan tag by tcpdump. The
vlan tag is inserted by the OVS in the host kernel.

Thanks for pointing to the patches. I will try them.

- Hui

On Wed, Apr 30, 2014 at 2:07 AM, Eugene Istomin <E.Istomin at edss.ee> wrote:

>  Hi,
>
>
>
> what hypervisor do you use?
>
> There are kernel patches like
> http://openvswitch.org/pipermail/dev/2013-December/035568.html ,
> http://patchwork.ozlabs.org/patch/324986/
>
> that improve VLAN tag handling inside VM.
>
> ---
>
> Best regards,
>
> Eugene Istomin
>
>
>
>
> On Tuesday, April 29, 2014 05:36:23 PM Hui Kang wrote:
>
> Hi, Justin,I used OVS 1.9.3. But there is nothing suspicious in the log
> when I grep for vlan in the log file.
>
>
> - Hui
>
>
>
> On Tue, Apr 29, 2014 at 5:28 PM, Justin Pettit <jpettit at nicira.com> wrote:
>
> On April 29, 2014 at 2:26:18 PM, Hui Kang (hkang.sunysb at gmail.com) wrote:
> > Hi,
> > I use iperf to test the 10G performance of OVS bridge with vlan tag added
> > on the vport for the VMs.
> >
> > On each machine, the OVS bridge are created on the Intel 82599 10G NIC. I
> > found the performance drops significantly when I added vlan tag on the
> > vport of both VMs.
> >
> > no vlan tag: 9.47 Gbps
> > add vlan tag: 3.96 Gbps
> >
> > Is this a normal behavior after adding vlan tag to the packet header?
>
> I don't think that should be happening.  What version of OVS are you
> running?  Do you see anything suspicious in your ovs-vswitchd.log?
>
> --Justin
>
>
>
>
>
>
>
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