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Re: [Xen-users] netback performance



This seems to have something to do with offloading gro/gso on VM and hypervisor - which works as long the VMs is on the same dom0, but when traffic egresses an openvswitch gre tunnel, the packets are segmented back to 1500 bytes, which could be the reason for this, and not the netback performance…
Still I have not been able to figure out why the packets are segmented or if there is actually a performance difference between virtio vs netback regarding pps.


On 23/07/2014, at 17.17.02, Kristoffer Egefelt <kristoffer@xxxxxxx> wrote:

Hi,

Right, traffic not leaving the dom0 seems not to be affected by this - but in this case:

- Two dom0s connected with 10G
- One VM (HVM/PV does not matter) on each dom0
- One vif in each VM

Unidirectional traffic between the two VMs reaches near line rate on mtu 1500 ~800.000 packets pr second.

I tried to tune the netback / dom0 alot, but I never saw a vif doing more than 200.000 pps … ?

Is virtio really that much faster - or am I doing something very wrong with XEN ?



On 23/07/2014, at 16.41.27, Eugene Istomin <e.istomin@xxxxxxx> wrote:

Hello,

 

>no reason I know of why Xen also couldn't do it.
We have 12-16 Gb/s for inter-Dom0 VMs, there are no slow network issues related to Xen 4.4 in case of inter-Dom0 & MTU 9000.

 

---
Best regards,
Eugene Istomin

On Wednesday, July 23, 2014 08:51:35 AM Steven Timm wrote:
> I have seen Xen do more than 1.5GBit/s on vm-to-vm performance
> within the same hypervisor. Never tried it on a machine with
> 10Gbit/s hardware. KVM is certainly capable of 10Gbit/s wire speed
> with virtio and we do it regularly, no reason I know of why Xen also
> couldn't do it.
>
> Steve
>
> On Wed, 23 Jul 2014, Kristoffer Egefelt wrote:
> > Hi,
> >
> > Until now I was under the impression that a VM could not move more than
> > ~200.000pps or ~1.5Gbit on mtu 1500 on one VIF - in XENs case due to the
> > netback process being single threaded.
> >
> > But here they apparently get line-rate 10G on a single vif one-core VM
> > (+800.000pps), using standard KVM and virtio (this is not documented in
> > the post, I asked them).
> >
> > /
> >
> > This seems almost unreal to me - but maybe I’m missing something.
> >
> > Is Xen currently able to do this ?
> >
> >
> > Thanks
> > Kristoffer
> > _______________________________________________
> > Xen-users mailing list
>
> ------------------------------------------------------------------
> Steven C. Timm, Ph.D (630) 840-8525
> Fermilab Scientific Computing Division, Scientific Computing Services Quad.
> Grid and Cloud Services Dept., Associate Dept. Head for Cloud Computing

 

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