Re: Everything You Know Is Wrong

["Alejandro R. Mosteo" <alejandro@mosteo.com>]

On 29/12/15 18:53, G.B. wrote:
> On 29.12.15 18:36, Dmitry A. Kazakov wrote:
>> On 2015-12-29 17:57, G.B. wrote:
>>
>>> The point is that, since order does not matter among these parallel
>>> computations, and since parallel loops are not just fantasy,
>>> the possibility of postponement follows from parallel loops.
>>
>> Ada does not have parallel loops.
>
> Ada is about to have parallel loops. Ada compilers already produce
> code for parallel execution of loop bodies on today's processors.

In this regard, just the other day I discovered Matlab's parfor, which 
as expected just parallelizes what would be a plain loop. It even emits 
some warnings about how the input data should be structured/used to 
minimize data transmission to the workers (which may be remote). I guess 
it would be interesting to look at how this and other languages do it.

-Álex.

>
>
>>> Consider F1 and F2 from a Pure package, X a variable of type T
>>> and T without progenitors:
>>>
>>>     declare
>>>        A : T := F1 (1,2,3);
>>>        B : T := F2 (X);
>>>     begin
>>>        G (A, B);
>>>     end;
>>>
>>> Is it impossible for a compiler to see that the initializing parts of
>>> the declarations of A and B are independent?
>>
>> No, because initialization of T may have side effects.
>
> I assume you meant Yes, impossible. But,
> if F1 and F2 are from a Pure package, is the compiler allowed to
> ignore side effects because the programmer specified Pure? I think
> that follows.
>
>> BTW, why do you believe that the same amount of computation performed
>> consecutively should require less energy or (not quite same) less
>> battery drain?
>
> Less energy at a certain point in time. Postpone calling sub if, say,
> a photocell should first be given time to recharge a battery while
> while regular operation continues, then call sub.
>
>