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

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.arch.embedded
Subject Re: C++ threads versus PThreads for embedded Linux on ARM micro
Date 2018-08-03 10:28 +0200
Organization A noiseless patient Spider
Message-ID <pk13mi$bog$1@dont-email.me> (permalink)
References (8 earlier) <pjv5ah$d7a$1@dont-email.me> <a9d6mdhea5csaqnmsdbmsn4jfuj7kdg4aq@4ax.com> <j_G8D.1977041$B36.32253@fx22.am4> <pjvs32$9uu$1@dont-email.me> <_WL8D.1467$Zc2.570@fx45.am4>

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On 03/08/18 00:52, Tom Gardner wrote:
> On 02/08/18 22:12, David Brown wrote:
>> On 02/08/18 19:14, Tom Gardner wrote:
>>> On 02/08/18 17:56, upsidedown@downunder.com wrote:
>>>> All you need is the ability to have stacks in RAM and in addition
>>>> instructions for loading and storing the stack pointer from/to memory.
>>>
>>> Unfortunately that is difficult to implement in C, so youngsters
>>> don't think of it.
>>>
>>
>> This particular youngster grew up on small microcontrollers programmed
>> in assembly.  
> 
> Ditto; neither of us are spring chickens.
> 
> The first computer I designed, while still an undergrad, had
> 128 bytes of memoy. I still have that ic :)

I have never designed a chip - though in my teens I once designed key
parts of a simple 4-bit cpu with a small instruction set.  I drew it all
out in two input NAND gates, on graph paper - including the single-cycle
multiplier.

> 
>> "All you need is the RAM" is not helpful when you have 512 bytes in
>> total, and the stack pointer is limited to accessing the first 128
>> bytes of that.  I have worked on microcontrollers where the context
>> switches involved in handling an interrupt could easily take 50 µs or
>> more - a proper RTOS would be far too high overhead.
>>
>> Of course you can have more minimal OS's with very limited features
>> (all the way down to "protothreads"), and perhaps cooperative
>> multi-tasking rather than pre-emptive.  But then you are not going to
>> have threads with multiple message queues like the ones under discussion.
> 
> Protothreads always strike me as being a kludge that is "justified"
> by the limitations of the software tools rather than the hardware
> limitations.

They are a way to get convenient coding structures from very little
software or hardware.  I haven't had a use for them myself, but I
suppose some people use them.

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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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