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Date: Tue, 3 Oct 2023 05:41:56 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: John Fastabend <john.fastabend@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>, bpf <bpf@vger.kernel.org>,
 Networking <netdev@vger.kernel.org>, "davidhwei@meta.com"
 <davidhwei@meta.com>
Subject: Re: Sockmap's parser/verdict programs and epoll notifications
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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..