Subject: PPP in user-space or kernel? was Re: autoconfiguration question
To: None <>
From: Jonathan Stone <jonathan@DSG.Stanford.EDU>
List: tech-kern
Date: 05/25/1997 16:23:09
On Sun, 25 May 1997 15:50:23 -0700, Jason Thorpe writes:

>On Mon, 26 May 1997 08:32:05 +1000 (EST) 
> wrote:
> > The main reason for moving this stuff into user-land is that PPP is
> > getting somewhat bloaty

>...this is a good argument for proper modularization, the ability to
>compile in support for only that which you want/need, and for a sane
>LKM interface... but I still think the cost of copying the data around
>is too high in practice.

The context switches (or latency, if you batch packets) can be painful
too.  Otherwise, yup. We really have to stop thinking of PPP as used
only on low-bandwidth links.  (And for some of the machines NetBSD is
used on, the threshold for ``low bandwidth'' is _very_ low, too).

I'd be OK with moving PPP link-level state control and per-protocol
control into userspace.  (If the link is up and not changing state,
then sending packets on it shouldn't involve PPP link-state.)  But
that just argues even more strongly for ``proper modularity''.

Jason's right here.