Re: C++ threads versus PThreads for embedded Linux on ARM micro

From	Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups	comp.arch.embedded
Subject	Re: C++ threads versus PThreads for embedded Linux on ARM micro
Date	2018-08-03 10:14 +0300
Organization	Tidorum Ltd
Message-ID	<fsidmuFdg5kU1@mid.individual.net> (permalink)
References	(7 earlier) <dkt5md5p1f7041qaush15drpe9k36ajke1@4ax.com> <pjv5ah$d7a$1@dont-email.me> <94fdd2e8-e1a4-48ff-9ffb-10fc21640439@googlegroups.com> <pjvrnl$7ge$1@dont-email.me> <ac23d398-ba9f-477a-a292-b98ff5c4b22c@googlegroups.com>

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On 18-08-03 00:22 , StateMachineCOM wrote:
> @David Brown: As they say: "you can lead a horse to water, but you
> can't make it drink". I rest my case.

At least this one juror decides in favour of David B.

All programs are state machines, but the "state" can be represented in 
various ways: as data ("reified") or as control flow ("sequential", 
"blocking"). Which is better depends on the problem to be solved; 
usually I end up with a mixture.

Sometimes system constraints force one to use more data-state than is 
optimal, and the code becomes an awful mess. I have in mind my last 
project but one, where the SW controls several devices over a 
MIL-STD-1553 bus, with a cyclic, frame-based schedule, running several 
sporadically activated concurrent activites, each of which usually 
requires several carefully timed bus commands and responses, spread over 
several bus cycles.

The nicest design would dedicate one thread to each such activity; after 
sending a command, the thread would wait (block) for the response, and 
would know, from its position in the algorithm, what to do with the 
response and what command to send next. But system constraints prohibit 
this number of threads, and thread switches, so all the state of the 
activities is reified into multiple state machines, activated once on 
every bus cycle, with switch/case statements that change the global 
state, increment counters, detect end of loops, retry failed commands, 
and so on and on. Yuck.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .

Thread

C++ threads versus PThreads for embedded Linux on ARM micro "gp.kiwi@gmail.com" <graeme.prentice@gmail.com> - 2018-07-20 04:01 -0700
  Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-07-20 20:19 +0200
    Re: C++ threads versus PThreads for embedded Linux on ARM micro graeme.prentice@gmail.com - 2018-07-20 15:54 -0700
      Re: C++ threads versus PThreads for embedded Linux on ARM micro Paul Rubin <no.email@nospam.invalid> - 2018-07-20 18:27 -0700
        Re: C++ threads versus PThreads for embedded Linux on ARM micro graeme.prentice@gmail.com - 2018-07-20 23:58 -0700
          Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-07-21 14:32 +0200
            Re: C++ threads versus PThreads for embedded Linux on ARM micro mac <acolvin@efunct.com> - 2018-07-26 19:37 +0000
          Re: C++ threads versus PThreads for embedded Linux on ARM micro Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-07-21 21:48 +0300
          Re: C++ threads versus PThreads for embedded Linux on ARM micro Rob Gaddi <rgaddi@highlandtechnology.invalid> - 2018-07-23 09:58 -0700
  Re: C++ threads versus PThreads for embedded Linux on ARM micro Les Cargill <lcargill99@comcast.com> - 2018-07-22 13:15 -0500
  Re: C++ threads versus PThreads for embedded Linux on ARM micro StateMachineCOM <statemachineguru@gmail.com> - 2018-07-27 08:51 -0700
    Re: C++ threads versus PThreads for embedded Linux on ARM micro "gp.kiwi@gmail.com" <graeme.prentice@gmail.com> - 2018-07-27 14:53 -0700
      Re: C++ threads versus PThreads for embedded Linux on ARM micro Paul Rubin <no.email@nospam.invalid> - 2018-07-27 15:23 -0700
      Re: C++ threads versus PThreads for embedded Linux on ARM micro StateMachineCOM <statemachineguru@gmail.com> - 2018-07-30 09:08 -0700
      Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-07-31 09:21 +0200
    Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-07-31 09:13 +0200
      Re: C++ threads versus PThreads for embedded Linux on ARM micro StateMachineCOM <statemachineguru@gmail.com> - 2018-07-31 15:16 -0700
        Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-08-01 07:53 +0200
        Re: C++ threads versus PThreads for embedded Linux on ARM micro pozz <pozzugno@gmail.com> - 2018-08-01 15:49 +0200
        Re: C++ threads versus PThreads for embedded Linux on ARM micro upsidedown@downunder.com - 2018-08-01 21:47 +0300
          Re: C++ threads versus PThreads for embedded Linux on ARM micro StateMachineCOM <statemachineguru@gmail.com> - 2018-08-01 12:11 -0700
            Re: C++ threads versus PThreads for embedded Linux on ARM micro Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-08-01 20:23 +0100
            Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-08-02 12:24 +0200
              Re: C++ threads versus PThreads for embedded Linux on ARM micro upsidedown@downunder.com - 2018-08-02 16:14 +0300
                Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-08-02 16:43 +0200
                Re: C++ threads versus PThreads for embedded Linux on ARM micro StateMachineCOM <statemachineguru@gmail.com> - 2018-08-02 09:12 -0700
                Re: C++ threads versus PThreads for embedded Linux on ARM micro Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-08-02 18:13 +0100
                Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-08-02 23:05 +0200
                Re: C++ threads versus PThreads for embedded Linux on ARM micro StateMachineCOM <statemachineguru@gmail.com> - 2018-08-02 14:22 -0700
                Re: C++ threads versus PThreads for embedded Linux on ARM micro Niklas Holsti <niklas.holsti@tidorum.invalid> - 2018-08-03 10:14 +0300
                Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-08-03 10:22 +0200
                Re: C++ threads versus PThreads for embedded Linux on ARM micro Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-08-02 23:48 +0100
                Re: C++ threads versus PThreads for embedded Linux on ARM micro upsidedown@downunder.com - 2018-08-02 19:56 +0300
                Re: C++ threads versus PThreads for embedded Linux on ARM micro Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-08-02 18:14 +0100
                Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-08-02 23:12 +0200
                Re: C++ threads versus PThreads for embedded Linux on ARM micro Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-08-02 23:52 +0100
                Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-08-03 10:28 +0200
                Re: C++ threads versus PThreads for embedded Linux on ARM micro Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-08-03 11:21 +0100
                Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-08-03 13:51 +0200
                Re: C++ threads versus PThreads for embedded Linux on ARM micro upsidedown@downunder.com - 2018-08-03 09:11 +0300
                Re: C++ threads versus PThreads for embedded Linux on ARM micro George Neuner <gneuner2@comcast.net> - 2018-08-04 03:00 -0400
                Re: C++ threads versus PThreads for embedded Linux on ARM micro Robert Wessel <robertwessel2@yahoo.com> - 2018-08-02 12:23 -0500
                Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-08-02 23:13 +0200
                Re: C++ threads versus PThreads for embedded Linux on ARM micro George Neuner <gneuner2@comcast.net> - 2018-08-04 03:08 -0400
              Re: C++ threads versus PThreads for embedded Linux on ARM micro Robert Wessel <robertwessel2@yahoo.com> - 2018-08-02 12:23 -0500
              Re: C++ threads versus PThreads for embedded Linux on ARM micro George Neuner <gneuner2@comcast.net> - 2018-08-02 14:15 -0400
                Re: C++ threads versus PThreads for embedded Linux on ARM micro Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-08-02 19:21 +0100
                Re: C++ threads versus PThreads for embedded Linux on ARM micro David Brown <david.brown@hesbynett.no> - 2018-08-02 23:18 +0200
                Re: C++ threads versus PThreads for embedded Linux on ARM micro Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-08-03 00:02 +0100
          Re: C++ threads versus PThreads for embedded Linux on ARM micro StateMachineCOM <statemachineguru@gmail.com> - 2018-08-01 12:28 -0700

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