On Wed, 2013-11-06 at 16:16 +0800, Herbert Xu wrote:

Instead of using perfectly sane 4K pages per frag to store guest to
guest traffic, we now end up using 1.5K frags, which that's why you
end up having to use the frag_list, WTF?

Sure, if your host has infinite amount of memory, we can remove all the
silly and expensive and bore some checks we added in the stack against
skb->truesize.

And yes, network stack will be faster.

But in real life, we have memory constraints.