Re: Sockmap's parser/verdict programs and epoll notifications

[Jakub Kicinski <kuba@kernel.org>]

On Mon, 02 Oct 2023 22:16:13 -0700 John Fastabend wrote:
> > This with the other piece we want from our side to allow running
> > verdict and sk_msg programs on sockets without having them in a
> > sockmap/sockhash it would seem like a better system to me. The
> > idea to drop the sockmap/sockhash is because we never remove progs
> > once they are added and we add them from sockops side. The filter
> > to socketes is almost always the port + metadata related to the
> > process or environment. This simplifies having to manage the
> > sockmap/sockhash and guess what size it should be. Sometimes we
> > overrun these maps and have to kill connections until we can
> > get more space.

That's a step in the right direction for sure, but I still think that
Google's auto-lowat is the best approach. We just need a hook that
looks at incoming data and sets rcvlowat appropriately. That's it.
TCP looks at rcvlowat in a number of places to make protocol decisions,
not just the wake-up. Plus Google will no longer have to carry their
OOT patch..