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Re: Resource revocation

From Paul Rubin <no.email@nospam.invalid>
Newsgroups comp.arch.embedded
Subject Re: Resource revocation
Date 2013-07-27 18:43 -0700
Organization Nightsong/Fort GNOX
Message-ID <7xhaffxxv5.fsf@ruckus.brouhaha.com> (permalink)
References (16 earlier) <avXIt.22876$FS6.20500@fx10.am4> <7xd2q3eij2.fsf@ruckus.brouhaha.com> <wZXIt.17660$GQ5.1861@fx22.am4> <7xa9l7txcd.fsf@ruckus.brouhaha.com> <EpZIt.5612$Sr7.5577@fx08.am4>

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Tom Gardner <spamjunk@blueyonder.co.uk> writes:
> In which case I expect that the system architecture and
> specification would be good, since h/w engineers automatically
> avoid many traps[*] that softies seem to actively throw
> themselves into.

I don't have any reason to doubt the hardware design was good, though
it's not my area and I didn't see into it very much.  The initial
software architecture may also have made sense at some level.  After a
decade or so of patches and upgrades by dozens of programmers, any
clarity had long since vanished.

> Or ugly C code might have been auto-generated 

It wasn't anything like that.  It was handwritten and too clever by
half.  They "optimized" all over the place without profiling anything to
know where the cycles were actually going.  I remember one module had to
check the status of a few hundred channels in some sorted order.  It had
a single C function around 20 pages long, full of clever coding tricks
and code duplication to avoid unnecessary work.  Of course it amounted
to a micro-optimized O(N**2) sorting algorithm smeared through all that
code (this particular module may have actually been chewing cycles, but
most weren't).  Replacing it with a reasonable algorithm made the code
1/4 of the size and orders of magnitude faster, optimizations not
needed.  Ericsson's codebase was apparently in sort of similar condition
when they switched from C to Erlang in the 1980's(?), so I guess this is
a familiar story.

> [*] especially those related to distributed interacting
> systems with long lifetimes

This wasn't really a distributed system.  It had two CPU's (primary and
failover) with a communication channel and some shared peripherals.
That aspect of the architecture wasn't too bad, but the upgrade/failover
code was somewhat horrendous since the stuff that had to be communicated
between the CPU's wasn't really localized in the codebase.  You had to
just hope that if you missed anything, it would show up in QA instead of
causing some subtle failure in the field.

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Resource revocation Don Y <this@isnotme.com> - 2013-07-25 12:23 -0700
  Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-25 12:51 -0700
    Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-25 15:00 -0700
      Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-25 19:38 -0700
        Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-25 22:12 -0700
          Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-25 23:37 -0700
            Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 01:13 -0700
              Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-26 02:48 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 04:19 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-26 09:46 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 10:21 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-26 19:30 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 11:56 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-26 20:08 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 13:11 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-26 12:31 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 11:08 -0700
                Re: Resource revocation Rob Gaddi <rgaddi@technologyhighland.invalid> - 2013-07-29 09:16 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-29 10:22 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 11:22 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-27 08:56 -0700
                Re: Resource revocation Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2013-07-26 19:25 +0200
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-26 10:51 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-26 19:21 +0100
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-26 11:50 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-26 19:42 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 12:43 -0700
                Does the Buddha have a real time nature? ;)  (was Resource revocation) Roberto Waltman <usenet@rwaltman.com> - 2013-07-26 17:06 -0400
                Re: Does the Buddha have a real time nature? ;)  (was Resource revocation) Don Y <this@isnotme.com> - 2013-07-26 17:12 -0700
                Re: Does the Buddha have a real time nature? ;)  (was Resource revocation) Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 09:44 +0100
                Re: Does the Buddha have a real time nature? ;)  (was Resource revocation) Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 09:45 +0100
                Re: Does the Buddha have a real time nature? ;)  (was Resource revocation) Don Y <this@isnotme.com> - 2013-07-27 12:28 -0700
                Re: Does the Buddha have a real time nature? ;)  (was Resource revocation) Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2013-07-27 14:11 +0200
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 12:40 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-26 21:29 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 13:52 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-26 22:55 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 17:22 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 10:02 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-27 09:29 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 18:20 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-27 12:48 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 22:57 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-27 16:18 -0700
                Re: Resource revocation Roberto Waltman <usenet@rwaltman.com> - 2013-07-31 16:33 -0400
                Re: Resource revocation upsidedown@downunder.com - 2013-07-27 22:53 +0300
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 22:42 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-27 16:41 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-27 16:49 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-28 08:39 +0300
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 23:11 -0700
                Re: Resource revocation Roberto Waltman <usenet@rwaltman.com> - 2013-07-31 16:15 -0400
                Re: Resource revocation upsidedown@downunder.com - 2013-08-01 00:13 +0300
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 15:16 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 23:05 +0100
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 15:37 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 23:38 +0100
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 16:08 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-28 01:16 +0100
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 18:43 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-28 09:01 +0300
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-27 15:21 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-27 23:07 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-26 12:00 -0700
                Re: Resource revocation stephenXXX@mpeforth.com (Stephen Pelc) - 2013-07-27 16:49 +0000
                Re: Resource revocation Richard Damon <Richard@Damon-Family.org> - 2013-07-28 18:31 -0400
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-28 15:51 -0700
                Re: Resource revocation Richard Damon <Richard@Damon-Family.org> - 2013-07-28 20:12 -0400
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-28 18:35 -0700
                Re: Resource revocation Richard Damon <Richard@Damon-Family.org> - 2013-07-29 00:10 -0400
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 00:23 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-29 01:05 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 12:07 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-30 01:11 +0300
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 15:20 -0700
                Re: Resource revocation Rob Gaddi <rgaddi@technologyhighland.invalid> - 2013-07-29 15:42 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 16:41 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-30 08:51 +0300
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-30 09:09 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 01:30 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-30 10:04 +0100
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-30 02:55 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 07:12 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-30 16:59 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 13:17 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-30 10:12 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-30 18:48 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 20:18 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-31 09:27 +0300
                Re: Resource revocation [long] Don Y <this@isnotme.com> - 2013-07-31 00:47 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-30 02:50 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-30 13:22 +0300
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 07:24 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 01:17 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-29 19:28 -0700
                Re: Resource revocation upsidedown@downunder.com - 2013-07-29 11:40 +0300
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 11:44 -0700
                Re: Resource revocation Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-07-29 20:56 +0100
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 13:16 -0700
                Re: Resource revocation Richard Damon <Richard@Damon-Family.org> - 2013-07-30 00:08 -0400
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-30 23:41 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-31 00:58 -0700
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-31 10:18 -0700
                Re: Resource revocation George Neuner <gneuner2@comcast.net> - 2013-08-02 06:19 -0400
                Re: Resource revocation Richard Damon <Richard@Damon-Family.org> - 2013-08-03 02:26 -0400
                Re: Resource revocation Paul Rubin <no.email@nospam.invalid> - 2013-07-28 19:31 -0700
                Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-29 00:44 -0700
  Re: Resource revocation Richard Damon <Richard@Damon-Family.org> - 2013-07-25 22:42 -0400
    Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-25 22:12 -0700
  Re: Resource revocation "Boudewijn Dijkstra" <sp4mtr4p.boudewijn@indes.com> - 2013-07-31 13:41 +0200
    Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-31 07:51 -0700
      Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-31 08:07 -0700
        Re: Resource revocation Anders.Montonen@kapsi.spam.stop.fi.invalid - 2013-07-31 15:55 +0000
          Re: Resource revocation Don Y <this@isnotme.com> - 2013-07-31 10:18 -0700
      Re: Resource revocation "Boudewijn Dijkstra" <sp4mtr4p.boudewijn@indes.com> - 2013-08-01 14:42 +0200
        Re: Resource revocation Don Y <this@isnotme.com> - 2013-08-01 14:34 -0700
      Re: Resource revocation upsidedown@downunder.com - 2013-08-02 09:08 +0300
        Re: Resource revocation Don Y <this@isnotme.com> - 2013-08-02 07:26 -0700

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