Re: gso: Attempt to handle mega-GRO packets

Michael S. Tsirkin
2013-11-07T05:53:50Z

On Wed, Nov 06, 2013 at 06:02:38PM -0800, Eric Dumazet wrote:
> On Thu, 2013-11-07 at 09:47 +0800, Herbert Xu wrote:
>
> > Say the system is fragmented sufficiently that you'll end up with
> > 0-order pages. In that case you'll only ever be able to coalesce
> > two packets.
>
> 4K page will contain 2 frags and they will coalesce.
>
> Performance will still be quite good.
>
> We probably add a tweak, to not have any hole in this case.
>
> >
> > Real systems that run for more than a day do end up with seriously
> > fragmented memory.
>
> Sure, but having shallow skbs in the first place help quite a bit.
>
> There is no perfect solution, unless of course you change virtio_net to
> provide different queues, with different frag sizes.
>
> Sort of what NIU driver uses.
>

I considered doing this but won't this mean packets can get reordered?
In practice we need to maintain ordering of RX frames within
a given flow, correct?

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MST