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Date:      Wed, 18 Jun 2003 12:47:33 -0500
From:      "Matthew D. Fuller" <fullermd@over-yonder.net>
To:        Poul-Henning Kamp <phk@phk.freebsd.dk>
Cc:        arch@freebsd.org
Subject:   Re: userland access to devices is moving!
Message-ID:  <20030618174733.GC10127@over-yonder.net>
In-Reply-To: <41012.1055950519@critter.freebsd.dk>
References:  <41012.1055950519@critter.freebsd.dk>

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On Wed, Jun 18, 2003 at 05:35:19PM +0200 I heard the voice of
Poul-Henning Kamp, and lo! it spake thus:
> 
> I sat down and hacked up a simple prototype to test the concept I
> have been rambling about for some years:  Going directly from
> filedescriptor to device driver thus bypassing the vnode, devfs and
> specfs layer.

Speaking as somebody whose reach of mailing lists notably exceeds his
grasp (as it always should be; otherwise what fun is it?), I often find
myself a little in the dark on what these sort of things really /mean/ to
the system in the end, and I think it would be a nice extension of these
sort of posts/proposals to have a sentence of summary, along the lines
of:

What does this change /mean/ to the system as a whole?  Is this
A) Cleaner code, so bugs can be found and fixed quicker and better,
B) Architectural improvement, so new features are easier to add on
   cleanly and well, or
C) A real-world performance improvement.  The benchmark you posted
   certainly shows a significant improvement in SOMETHING; but is it a
   something that will make mail servers or web servers or file servers
   or workstations perk up?

I realize that they're not really exclusive conditions, and are mostly
intertangled.  And, for that matter, that most changes don't get done
because of A, B, C, or any combination thereof, but more often because
"This is the ugliest mess I've ever seen and it's been haunting my dreams
for years, and I anyway I thought it would be fun to mess with."  But I
for one would appreciate a quick note of a higher-level view of where
this can move us.


Of course this means I'm out of my depth.  But everybody needs a hobby
:-}



-- 
Matthew Fuller     (MF4839)   |  fullermd@over-yonder.net
Systems/Network Administrator |  http://www.over-yonder.net/~fullermd/

"The only reason I'm burning my candle at both ends, is because I
      haven't figured out how to light the middle yet"



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