Re: gso: Attempt to handle mega-GRO packets

Eric Dumazet
2013-11-06T15:01:15Z

On Wed, 2013-11-06 at 21:12 +0800, Herbert Xu wrote:

> I take that back. While the original patch was seriously broken,
> it has since been fixed by the coalescing patch that Jason Wang
> wrote.
>

Patch was not 'broken', but a step into the right direction. I am very
sorry if you think otherwise.

> It's still pretty weird to be dividing page frags into 1500-byte
> chunks and then merging back up to 4K but at least it should do the
> right thing now.

Have you thought about arches having PAGE_SIZE=65536, and how bad it is
to use a full page per network frame ? It is lazy and x86 centered.

So after our patches, we now have an optimal situation, even on these
arches.

On x86, a full 64KB GSO packet will now fit in 2 (or 3) frags allocated
in 32KB pages (order-3) in fast path (ie if there is not high memory
pressure)

According to our tests, performance is better on x86, and virtio_net now
is usable on arches with PAGE_SIZE=65536