OT: This Swift thing

[Steven D'Aprano]

On Sun, 08 Jun 2014 23:32:33 -0700, Rustom Mody wrote:

> On Monday, June 9, 2014 9:50:38 AM UTC+5:30, Steven D'Aprano wrote:
>> On Sun, 08 Jun 2014 19:24:52 -0700, Rustom Mody wrote:
>> 
>> 
>> > On Monday, June 9, 2014 7:14:24 AM UTC+5:30, Steven D'Aprano wrote:
>> >> CPU technology is the triumph of brute force over finesse.
>> > 
>> > If you are arguing that computers should not use millions/billions of
>> > transistors, I wont argue, since I dont know the technology.
>> 
>> No. I'm arguing that they shouldn't convert 90% of their energy input
>> into heat.
>> 
>> 
> Strange statement.
> What should they convert it into then?

Useful work, duh.

Everything *eventually* gets converted to heat, but not immediately. 
There's a big difference between a car that gets 100 miles to the gallon, 
and one that gets 1 mile to the gallon. Likewise CPUs should get more 
"processing units" (however you measure them) per watt of electricity 
consumed.

See, for example:

http://www.tomshardware.com/reviews/fx-power-consumption-efficiency,3060.html

http://en.wikipedia.org/wiki/Performance_per_watt

Quote:

    Theoretically, room‑temperature computer memory operating 
    at the Landauer limit could be changed at a rate of one 
    billion bits per second with only 2.85 trillionths of a 
    watt of power being expended in the memory media. Modern 
    computers use millions of times as much energy.

    http://en.wikipedia.org/wiki/Landauer's_principle


Much to my surprise, Wikipedia says that efficiency gains have actually 
been *faster* than Moore's Law. This surprises me, but it makes sense: if 
a CPU uses ten times more power to perform one hundred times more 
computations, it has become much more efficient but still needs a much 
bigger heat sink.

http://en.wikipedia.org/wiki/Koomey's_law


> JFTR: Information processing and (physics) energy are about as
> convertible as say: "Is a kilogram smaller/greater than a mile?"

(1) I'm not comparing incompatible units. And (2) there is a fundamental 
link between energy and entropy, and entropy is the reverse of 
information. See Landauer's Principle, linked above. So information 
processing and energy are as intimately linked as (say) current and 
voltage, or mass and energy, or momentum and position.



-- 
Steven D'Aprano
http://import-that.dreamwidth.org/