Re: [PATCH net-next 0/6] kcm: Kernel Connection Multiplexor (KCM)

[Florian Westphal <fw@strlen.de>]

David Miller <davem@davemloft.net> wrote:
> From: Florian Westphal <fw@strlen.de>
> Date: Tue, 24 Nov 2015 16:27:44 +0100
> 
> > Aside from Hannes comment -- KCM seems to be tied to the TLS work, i.e.
> > I have the impression that KCM without ability to do TLS in the kernel
> > is pretty much useless for whatever use case Tom has in mind.
> 
> I do not get this impression at all.
> 
> Tom's design document in the final patch looks legitimately what the
> core use case is.

You mean
https://patchwork.ozlabs.org/patch/547054/ ?

Its a well-written document, but I don't see how moving the burden of
locking a single logical tcp connection (to prevent threads from
reading a partial record) from userspace to kernel is an improvement.

If you really have 100 threads and must use a single tcp connection
to multiplex some arbitrarily complex record-format in atomic fashion,
then your requirements suck.

Now, arguably, maybe the requirements of Toms use case are restricted
/cannot be avoided.

But that still begs the question: Why should mainline care?

Once its in, next step will be 'my single tcp connection that I use
for multiplexing via KCM now has requirement to use TLS'.

How far are you willing to take the KCM concept?