Re: [9fans] PDP11 (Was: Re: what heavy negativity!)

[Bakul Shah <bakul@bitblocks.com>]

On Tue, 09 Oct 2018 10:45:37 -0700 Lyndon Nerenberg <lyndon@orthanc.ca> wrote:
Lyndon Nerenberg writes:
> Bakul Shah writes:
>
> > One thing I have mused about is recasting plan9 as a
> > microkernel and pushing out a lot of its kernel code into user
> > mode code.  It is already half way there -- it is basically a
> > mux for 9p calls, low level device drivers, VM support & some
> > process related code.
>
> Somewhat related to this ... after reading some papers on
> TCP-in-user-space implementations, I've been thinking about how an
> interface that supported fast/secure page flipping between the
> kernel and process address space would change how we do things.
>
> E.g. right now Plan 9 suffers from a *lot* of data copying between
> the kernel and processes, and between processes themselves.  If we
> could eliminate most of that copying, things would get a lot faster.
> Dealing with the security issues isn't trivial, but the programmer
> time going into eeking out the last bit of I/O throughput of the
> current scheme could be redirected.

Funny you say this. I wrote I wanted memory mapping to avoid
having to copy data multiple times but then deleted it,
thinking it would detract from the main point.

Actually I want this even without any major redesign!

> If it works, this would reduce the kernel back to handling
> process/memory management, and talking to the hardware.  Not a
> micro-kernel, but just as good from a practical standpoint.

Some of this process/memory management can be delegated to
user code as well.