From: Larry McVoy <lm@mcvoy.com>
To: Andrew Warkentin <andreww591@gmail.com>
Cc: tuhs@tuhs.org
Subject: Re: [TUHS] A/UX [was Linux is on-topic]
Date: Mon, 20 Jul 2020 18:50:57 -0700 [thread overview]
Message-ID: <20200721015057.GV26294@mcvoy.com> (raw)
In-Reply-To: <CAD-qYGriDJ+=8NiJE1X1P7P_2kMYKzx1zmM01DesPF5MeK7hmA@mail.gmail.com>
On Mon, Jul 20, 2020 at 06:54:40AM -0600, Andrew Warkentin wrote:
> On 7/20/20, Larry McVoy <lm@mcvoy.com> wrote:
> > This isn't quite the same but Victor Yodaiken wrote a real time kernel
> > that ran all of Linux as a user process. Super cool idea and it worked
> > great, he would demo it sampling the parallel port while Linux was running
> > some X11 perf thing, tarring up /usr and untarring on nfs://server/tmp/usr
> > and doing a ftp transfer. Basically beating the crap out of Linux as
> > hard as he could while running a real time sampler and it never missed.
> >
> > Clem should pay attention, in my opinion, this is how you do Unix and
> > real time. Because Unix is time sharing and throughput, that is the
> > opposite of what real time is. Wedging real time into Unix is a mistake.
> >
>
> QNX manages to do realtime fairly decently while still being
> Unix-like, although it's certainly not a conventional Unix. With a
> multi-server OS with a properly designed microkernel, it is possible
> for realtime threads to more or less ignore the fact that they're
> running on a Unix-like OS (provided that they can access some kind of
> IPC API that closely matches that of the kernel) since all the OS
> services other than the microkernel are running beside them at
> non-realtime priorities, and not underneath them as in a conventional
> OS. It's kind of doing the same thing as running a Unix kernel as a
> process under a realtime kernel, but the Unix environment is
> implemented by servers and libraries instead of a monolithic kernel.
QNX is awesome.
I was friends with Dan Hildebrandt, he was one of the 3 people who were
allowed to touch the microkernel code. That kernel could fit easily in
a 4K instruction cache and leave room for other processes. They measured
everything in cache misses, every commit had them thinking about cache
misses.
I'm definitely a unikernel guy but I had mad respect for QNX, Dan and
I would talk often about stuff, like how would this work in your world
and how would it work in my world. The QNX core team was amazing.
Sadly, we lost Dan to brain cancer (I think) in 1998.
--
---
Larry McVoy lm at mcvoy.com http://www.mcvoy.com/lm
next prev parent reply other threads:[~2020-07-21 1:52 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-17 18:08 [TUHS] H.J. Lu Bootable Root & Base System disks Norman Wilson
2020-07-17 18:14 ` John Cowan
2020-07-17 18:19 ` Larry McVoy
2020-07-17 19:53 ` [TUHS] Linux is on-topic Warren Toomey
2020-07-17 19:57 ` Larry McVoy
2020-07-17 20:00 ` Adam Thornton
2020-07-17 20:04 ` Larry McVoy
2020-07-17 20:03 ` Dan Cross
2020-07-17 23:31 ` A. P. Garcia
2020-07-19 10:26 ` emanuel stiebler
2020-07-17 20:07 ` Warren Toomey
2020-07-17 20:12 ` Warner Losh
2020-07-17 20:19 ` Clem Cole
2020-07-19 9:54 ` Sergio Pedraja
2020-07-17 20:08 ` Michael Kjörling
2020-07-17 20:55 ` Grant Taylor via TUHS
2020-07-17 21:28 ` Michael Kjörling
2020-07-18 20:22 ` Ed Carp
2020-07-18 20:29 ` Warner Losh
2020-07-19 2:31 ` Gregg Levine
2020-07-19 3:46 ` Wesley Parish
2020-07-19 4:42 ` Grant Taylor via TUHS
2020-07-19 18:01 ` Michael Parson
2020-07-20 8:47 ` [TUHS] A/UX [was Linux is on-topic] arnold
2020-07-20 9:46 ` Arno Griffioen
2020-07-20 16:35 ` Arthur Krewat
2020-07-20 17:44 ` Arno Griffioen
2020-07-20 19:07 ` Rich Morin
2020-07-20 19:45 ` Al Kossow
2020-07-20 19:49 ` Al Kossow
2020-07-24 0:01 ` Chris Hanson
2020-07-20 20:20 ` Ed Carp
2020-07-20 21:02 ` John Cowan
2020-07-20 22:27 ` Ed Carp
2020-07-24 0:04 ` Chris Hanson
2020-07-31 23:02 ` Dave Horsfall
2020-07-31 23:12 ` Richard Salz
2020-08-01 1:36 ` Larry McVoy
2020-08-01 16:08 ` Nemo Nusquam
2020-08-01 17:01 ` Arthur Krewat
2020-08-13 0:00 ` Dave Horsfall
2020-08-13 1:47 ` Larry McVoy
2020-08-13 3:15 ` Grant Taylor via TUHS
2020-08-13 4:02 ` Larry Cashdollar via TUHS
2020-08-31 21:12 ` Dave Horsfall
2020-09-03 14:10 ` Michael Parson
2020-08-13 1:53 ` Nemo Nusquam
2020-08-13 17:14 ` Dan Cross
2020-08-13 17:19 ` Henry Bent
2020-08-13 17:58 ` Warner Losh
2020-08-13 20:04 ` John Cowan
2020-08-13 20:52 ` Dan Cross
2020-08-14 17:31 ` Paul Winalski
2020-08-15 1:24 ` Dave Horsfall
2020-08-18 13:57 ` Derek Fawcus
2020-08-18 14:11 ` John Cowan
2020-08-31 21:20 ` Dave Horsfall
2020-08-13 19:18 ` Adam Thornton
2020-08-13 19:28 ` Warner Losh
2020-08-13 20:15 ` [TUHS] AIX link repost [was " Charles H Sauer
2020-08-13 20:09 ` [TUHS] " Rich
2020-08-13 20:16 ` Larry McVoy
2020-08-13 20:17 ` Dr Iain Maoileoin
2020-08-14 1:04 ` Christopher Browne
2020-08-14 17:18 ` Jim Capp
2020-08-14 17:37 ` Jim Capp
2020-08-14 17:39 ` Jon Steinhart
2020-08-15 0:33 ` Rich
2020-08-15 1:20 ` Larry McVoy
2020-08-15 2:08 ` Dave Horsfall
2020-08-15 2:47 ` Warner Losh
2020-08-15 17:44 ` Paul Winalski
2020-08-15 12:05 ` Thomas Paulsen
2020-08-15 1:33 ` Jon Steinhart
2020-08-15 2:02 ` Dave Horsfall
2020-08-15 2:45 ` Andrew Hume
2020-08-15 16:55 ` William Cheswick
2020-08-15 3:29 ` Larry McVoy
2020-08-15 1:40 ` Gregg Levine
2020-08-13 22:24 ` Grant Taylor via TUHS
2020-07-24 0:02 ` Chris Hanson
2020-07-20 9:48 ` Andrew Warkentin
2020-07-20 11:49 ` Larry McVoy
2020-07-20 14:36 ` Clem Cole
2020-07-20 17:24 ` John Cowan
2020-07-20 22:11 ` Ed Carp
2020-07-21 1:04 ` Larry McVoy
2020-07-22 3:13 ` tytso
2020-07-22 5:40 ` Bakul Shah
2020-07-22 14:16 ` Larry McVoy
2020-07-20 12:32 ` Derrik Walker v2.0
2020-07-20 12:54 ` Andrew Warkentin
2020-07-21 1:50 ` Larry McVoy [this message]
2020-07-21 2:30 ` Gregg Levine
2020-07-22 3:44 ` Jason
2020-07-22 12:23 ` Derrik Walker v2.0
2020-07-20 14:28 ` Clem Cole
2020-07-22 3:50 ` Jason
2020-07-22 4:26 ` Henry Bent
2020-07-24 0:10 ` Chris Hanson
2020-07-20 0:24 ` [TUHS] Linux is on-topic Ed Carp
2020-07-22 3:41 ` Jason
2020-07-22 16:15 ` Michael Parson
2020-07-18 3:34 ` Tomasz Rola
2020-07-18 16:45 ` Christopher Browne
2020-07-19 7:32 ` Lars Brinkhoff
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