[Fedora-xen] netloop

[Ben]

Will this decrease or increase the chance of a domU loosing its network 
and the dom0 complaining about memory squeezes in the netback driver?

On Mon, 16 Apr 2007, Mark McLoughlin wrote:

> On Sat, 2007-04-14 at 19:12 +0100, Daniel P. Berrange wrote:
>
>> For compatability with FC5/6 we need to keep using network-bridge in the
>> default RPM setup. What we're trying to do is alter the network-bridge
>> script so that it doesn't need to use the netloop module. Part of this
>> work involves kernel changes to the way the Xen network module transfer
>> data to avoid some potential denial-of-service conditions that arise if
>> you're not using netloop.
>
> 	Just to elaborate ...
>
> 	The only reason netloop exists is to prevent the netback driver from
> "seizing up" if packets from DomU, destined for Dom0, are queued up
> indefinitely in Dom0 socket buffers causing hypervisor resources (grant
> table entries?) to be exhausted. The netloop solution is to copy packets
> from DomU just before they are delivered to Dom0's networking stack.
>
> 	The new solution is for netback to keep track of packets and to
> periodically copy any packets which have been queued up for too long.
> That way you don't need the netloop device at all.
>
> Cheers,
> Mark.
>
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