Re: Everything You Know Is Wrong

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 2015-12-29 14:50, G.B. wrote:
> On 29.12.15 13:36, Dmitry A. Kazakov wrote:
>> On 2015-12-29 12:42, G.B. wrote:
>>
>>> The hardware people do a lot to reduce energy needs.  The software
>>> people could add to that.
>>
>> I don't think so. Software is too costly and too volatile. Any potential
>> win is negligible and will be overtaken by new hardware in just one year.
>
> The managers of the billion $ computer companies have been
> addressing battery related running times for years already. Suppose
> that a compiler optimizes a program for energy consumption. So, no
> big batteries are needed.

In what sense? Less battery drain? 0.1%? The point that at the 
instruction level, if we are talking about optimization, not software 
redesign, no optimization could give you anything visible. With 
redesign, you could probably get 1% bought by massive software problems, 
as if we had only few today.

What does reduce energy consumption is the hardware architecture. E.g. 
designs with circuits having their own micro power sources. In a 
massively parallel system with distributed power supplies you will get 
better power management for free.

>>> For example, if two subprograms are independent
>>> and their execution can be postponed until a third one needs their
>>> results,
>>
>> Firstly, you cannot know that.
>
> Independence of subprograms can follow from an abstract design
> and from a solution, both of which the programmers know.

The compiler must become an oracle, not just programmer's mind reader, 
to guess that a subprogram call can be postponed.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de