Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.arch.embedded > #27931

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

Subject Re: C++ threads versus PThreads for embedded Linux on ARM micro
Newsgroups comp.arch.embedded
References (9 earlier) <a9d6mdhea5csaqnmsdbmsn4jfuj7kdg4aq@4ax.com> <j_G8D.1977041$B36.32253@fx22.am4> <pjvs32$9uu$1@dont-email.me> <_WL8D.1467$Zc2.570@fx45.am4> <pk13mi$bog$1@dont-email.me>
From Tom Gardner <spamjunk@blueyonder.co.uk>
Message-ID <l0W8D.1699490$tw.170430@fx42.am4> (permalink)
Organization virginmedia.com
Date 2018-08-03 11:21 +0100

Show all headers | View raw

On 03/08/18 09:28, David Brown wrote:
> 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.

Mine was 6800 based. Just about everything was "suboptimal" - except
that it worked and I learned a heck of a lot.

I later designed a single-purpose machine using 2900 bit-slices,
but it was never implemented.

> 
>>
>>> "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.

That's my (lack of) experience, but the requirement that all
context switches are in the top level code (i.e. not a function)
doesn't strike me as convenient. I know why it is "necessary",
but that doesn't change the inconvenience.

Back in 1982 I was using cooperative multitasking with C threads
on a Z80 (or PDP11 or whatever was convenient), with a little
bit of assembler to save/restore the stacks and other context.
That always seemed pretty natural - provided I used message
passing (with timeouts) for large-scale flow control.

Back to comp.arch.embedded | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

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

csiph-web