virtio-net zero-copy

virtio-net zero-copy

[Raju Srivastava]

Greetings,

Could someone let me know if current virtio-net supports zero-copy? I
see some discussion here:
http://thread.gmane.org/gmane.comp.emulators.kvm.devel/28061/
(copyless virtio net thoughts) and it looks like the copyless
virtio-net is not supported by KVM yet. If this is true, then is there
any plan to add the zero copy to the virtio-net?

I use KVM in 10G network environment and found the CPU usage is
saturated when network traffic becomes heavy. The native Linux under
the same load only consumes less than 10% CPU.

Thanks in advance,
Raju

Re: virtio-net zero-copy

[Avi Kivity]

Raju Srivastava wrote:
> Greetings,
>
> Could someone let me know if current virtio-net supports zero-copy? I
> see some discussion here:
> http://thread.gmane.org/gmane.comp.emulators.kvm.devel/28061/
> (copyless virtio net thoughts) and it looks like the copyless
> virtio-net is not supported by KVM yet. 

That is correct.

> If this is true, then is there
> any plan to add the zero copy to the virtio-net?
>   

Yes, but it will be a difficult journey.

> I use KVM in 10G network environment and found the CPU usage is
> saturated when network traffic becomes heavy. The native Linux under
> the same load only consumes less than 10% CPU.
>   

Running the latest guest and host software (both qemu and kernel) will 
improve things somewhat.


-- 
error compiling committee.c: too many arguments to function

Re: virtio-net zero-copy

[Raju Srivastava]

On Mon, May 18, 2009 at 10:00 PM, Avi Kivity <avi@redhat.com> wrote:
> Raju Srivastava wrote:
>>
>> Greetings,
>>
>> Could someone let me know if current virtio-net supports zero-copy? I
>> see some discussion here:
>> http://thread.gmane.org/gmane.comp.emulators.kvm.devel/28061/
>> (copyless virtio net thoughts) and it looks like the copyless
>> virtio-net is not supported by KVM yet.
>
> That is correct.

Thank you for letting me know this.

>> If this is true, then is there
>> any plan to add the zero copy to the virtio-net?
>>
>
> Yes, but it will be a difficult journey.

That's great. I'm looking forward to it. It's said Xen NetChannel 2
has some new features including the zero-copy. Though it would be a
difficult journey, it's really worth, right?

Thanks & Regards,
Raju