Re: Robert Dewar's great article about the Strengths of Ada over other langauges in multiprocessing!

[gpriv@axonx.com]

On Mar 15, 9:29 am, Maciej Sobczak <see.my.homep...@gmail.com> wrote:
> On 15 Mar, 03:29, gp...@axonx.com wrote:
>
> > IMHO it should not be keeping compiler designers from flushing the
> > contents of the registers down to lowest level
>
> Do you know that it can cost you two orders of magnitude of
> performance loss?
>
> > Performance penalties should not be a cover for not
> > doing this.
>
> On the contrary. Otherwise it would make no sense to introduce
> multicore architectures at all.

Performance is an issue in less than 1% of our code.  You may be in
different application though (however I doubt your numbers will be
that different)  We usually locate this 1 % and concentrate on it
still remaining well within the standard.  You must be a total idiot
to use volatile there or allow context switches.

>
> > What also seems to be alarming is proliferation of
> > architecture specificity into the programming techniques.
>
> No, there is no specificity. I have an impression that you still try
> to keep the volatile mess and then declare that the platform specifity

Your impression is totally wrong. My use of volatile may went 2-3 time
within 50KLOC program.  And as you may notice I don't use C++ in
preemtive environment any longer so issue is over.


> breaks your code, but the truth is totally inverse - you have broken
> code, period. That's it - don't expect compiler vendors to "fix the
> world" and penalize those who do things correctly.
> If you write correct code (yes, forget once and for all the volatile
> keyword), there is absolutely no architecture specificity to worry
> about.
>
> > What will happen when architecture change?
>
> Nothing. Correct programs will still work and broken programs will
> still be broken.

It's harder to formulate correctness that's all


>
> > C started as a language for very simple microprocessor architecture
> > language.  Now architectures outgrew what the language was originally
> > designed for.
>
> No, you can still target modern architectures with this "outdated"
> language. Just do it right. Interestingly, this also applies to Ada
> (wow! I've managed to keep the discussion on-topic! ;-) ).
>
> > Practitioners are simply patching things up trying to
> > make 12-year's old pants to fit on 16-years old boy.
>
> Yes, you are unfortunately right here. Practitioners have to worry
> about truckloads of broken code.
>
> --
> Maciej Sobczak *www.msobczak.com*www.inspirel.com