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From: Adam Thornton <athornton@gmail.com>
To: Warner Losh <imp@bsdimp.com>,
	The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] ATC/OSDI'21 joint keynote: It's Time for Operating Systems to Rediscover Hardware (Timothy Roscoe)
Date: Fri, 3 Sep 2021 10:10:57 -0700	[thread overview]
Message-ID: <CAP2nic2O5sDi3UQzD=9cpjQa1bxosLt_4OG6WRWuQs4Gjp4-4Q@mail.gmail.com> (raw)
In-Reply-To: <CANCZdfpdX=ajS=rrJSc4Zx98BuAhHJJttwuwTzU4EHyKM_0s0g@mail.gmail.com>

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Much of the problem, I think, is that:

1) an idealized PDP-11  (I absolutely take Warner's point that that
idealization never really existed) is a sufficiently simple model that a
Bear Of Little Brain, such as myself, can reason about what's going to
happen in response to a particular sequence of instructions, and get fairly
proficient in instructing the machine to do so in a non-geological
timeframe.

2) a modern CPU?  Let alone SoC?  Fuggedaboutit unless you're way, way
smarter than I am.  (I mean, I do realize that this particular venue has a
lot of those people in it...but, really, those are people with
extraordinary minds.)

There are enough people in the world capable of doing 1 and not 2 that we
can write software that usually mostly kinda works and often gets stuff
done before collapsing in a puddle of nasty-smelling goo.  There aren't
many people at all capable of 2, and as the complexity of systems
increases, that number shrinks.

In short, this ends up being the same argument that comes around every so
often, "why are you people still pretending that the computer is a PDP-11
when it clearly isn't?"  Because, as with the keys and the streetlight,
that's what we have available to us.  Only a grossly oversimplified model
fits into our heads.

Adam

On Fri, Sep 3, 2021 at 8:57 AM Warner Losh <imp@bsdimp.com> wrote:

>
>
> On Wed, Sep 1, 2021 at 4:00 PM Dan Cross <crossd@gmail.com> wrote:
>
>> I'm curious about other peoples' thoughts on the talk and the overall
>> topic?
>>
>
> My comment is that the mental map that he presents has always been a lie.
> At least it's been a lie from a very early time.
>
> Even in Unibus/Qbus days, the add-in cards had some kind of processor
> on it from an early time. Several of the VAX boards had 68000 or similar
> CPUs that managed memory. Even the simpler MFM boards had buffer
> memory that needed to be managed before the DMA/PIO pulled it out
> of the card. There's always been an element of different address spaces
> with different degrees of visibility into those address spaces.
>
> What has changed is all of these things are now on the SoC die so
> you have good visibility (well, as good as the docs) into these things.
> The number of different things has increased, and the for cross domain
> knowledge has increased.
>
> The simplistic world view was even inaccurate at the start....
>
> Warner
>

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  reply	other threads:[~2021-09-03 17:11 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-01 21:58 Dan Cross
2021-09-02  8:42 ` Tony Finch
2021-09-03  0:19   ` John Cowan
2021-09-03  3:24     ` Douglas McIlroy
2021-09-03 13:21       ` Theodore Ts'o
2021-09-08 11:14         ` Tony Finch
2021-09-16 19:27         ` Dan Cross
2021-09-17  0:34           ` Theodore Ts'o
2021-09-17  0:44             ` Larry McVoy
2021-09-17 17:07               ` Bakul Shah
2021-09-17  1:33             ` Dan Cross
2021-09-02 15:41 ` Kevin Bowling
2021-09-02 20:12   ` Marshall Conover
2021-09-03 15:56 ` Warner Losh
2021-09-03 17:10   ` Adam Thornton [this message]
2021-09-03 17:28     ` Larry McVoy
2021-09-03 17:42       ` John Floren
2021-09-03 19:02       ` Lawrence Stewart
2021-09-03 19:11       ` Clem Cole
2021-09-03 17:46     ` [TUHS] ATC/OSDI'21 joint keynote: It's Time for Operating Systems to Rediscover Hardware [ really a comment on SoCs ] Jon Steinhart
2021-09-16 18:38 ` [TUHS] ATC/OSDI'21 joint keynote: It's Time for Operating Systems to Rediscover Hardware (Timothy Roscoe) Dan Cross
2021-09-16 19:34   ` Jon Steinhart
2021-09-16 19:41     ` Larry McVoy
2021-09-16 23:14       ` Marshall Conover
2021-09-16 23:44         ` Rob Pike
2021-09-17  0:37           ` Larry McVoy
2021-09-17  1:38         ` Jon Steinhart
2021-09-17  3:54         ` John Cowan
2021-09-16 23:45       ` Jon Steinhart
2021-09-17  0:06         ` Al Kossow
2021-09-17  4:06           ` John Cowan
2021-09-17  4:18             ` Al Kossow
2021-09-17  0:32         ` Larry McVoy
2021-09-16 23:54       ` David Arnold
2021-09-17  1:10         ` Jon Steinhart
2021-09-17  1:28           ` Larry McVoy
2021-09-17  1:40             ` Jon Steinhart
2021-09-17  2:04               ` Larry McVoy
2021-09-17  2:21                 ` Jon Steinhart
2021-09-17  2:48           ` Theodore Ts'o
2021-09-17 17:39         ` Bakul Shah
2021-09-17 17:51           ` Jon Steinhart
2021-09-17 18:07             ` Larry McVoy
2021-09-17 21:03               ` Derek Fawcus
2021-09-17 22:11                 ` Larry McVoy
2021-09-19  4:05                   ` Theodore Ts'o
2021-09-17 18:34             ` Bakul Shah
2021-09-17 18:56               ` Jon Steinhart
2021-09-17 19:16                 ` Bakul Shah
2021-09-17 19:35                   ` Jon Steinhart
2021-09-17 15:56     ` Bakul Shah
2021-09-17 18:24       ` ron minnich

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