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Why Do Computers Use So Much Energy?

blogs.scientificamerican.com

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Re: Why Do Computers Use So Much Energy?

#121

Post by JohnJamesRambo »

lucideer wrote: post #12

> Precise estimates vary, but currently about 5 percent of all energy consumption in the U.S. goes just to running computers 30% goes on transport. > the human brain is a computer. This particular computer uses some 10–20 percent of all the calories that a human consumes So society's computer uses 5 percent and our own, evolved over millions of years, uses up to 20. I'm not saying computers can't or shouldn't be made…

The human brain is a hell of a lot more powerful than a computer.

https://bgr.com/2016/02/27/power-of-the-human-brain-vs-super...

Re: Why Do Computers Use So Much Energy?

#124

Post by jamiek88 »

gowld wrote: post #116
mikeash wrote: post #76

Earlier quoted context omitted.

It would make more sense to compare absolute numbers. A brain uses about 20W. A modern computer has similar consumption, but is many orders of magnitude less powerful.

My brain (or even my whole body) can't play HD video.

No, it plays way better than that.

Our eyes do not see. Our brains do. And the upscalimg from limited data is amazing!

Re: Why Do Computers Use So Much Energy?

#128

Post by devmacrile »

peeters wrote: post #105
cfallin wrote: post #88

Earlier quoted context omitted.

Why not, though? Energy is energy -- we (humans) oxidize food, basically burning it slowly, to power our bodies. Whether the energy is carried by glucose/ATP or electric current is just an implementation detail. Comparisons are frequently made in other domains as well -- e.g., cyclists measure power outputs in watts. The rule of thumb I've understood is that the brain runs on about 20 watts (peak power), and a human…

One is saying how much computers use of a global resource pool, the other is how much brains use of their host body. They're completely different things so it doesn't make sense to compare those two percentages. If you wanted to compare them, cite the percent that the CPU uses of its PSU, or cite the percent that human brains use of global energy consumption. Otherwise they're completely different things that have no…

Exactly. It's a meaningless and even misleading analogy.

If forced to draw a comparison, you could maybe talk about the energy dissipation of a single neuron and compare that to, say, the energy dissipation of a single transistor. And in that case, considering a human brain is powered by something on the order of 10^10 neurons, the energy efficiency of the brain comes out looking pretty good.

Re: Why Do Computers Use So Much Energy?

#129

Post by fovc »

acallan wrote: post #50
simias wrote: post #45

Earlier quoted context omitted.

>So society's computer uses 5 percent and our own, evolved over millions of years, uses up to 20. This comparison doesn't make a lot of sense to me. It's not even comparing apples to oranges, it's comparing apples to the concept of taste. Furthermore these percentages don't really tell you much regarding efficiency, I'm sure there are less developed societies where computers count for less than 5% of all energy consu…

Calories and can be converted to Joules. The amount of energy to run a computer (a human computer or a physical one) is interesting to me personally, as is comparing the amount of extra calories (and thus, extra emissions) it costs me to ride my bike 20 miles to work vs. driving a gasoline car.

Agriculture + metabolism has a much lower emissions per km than gas powered cars.

Also, your emissions are ultimately plant based, so the only real net emissions are due to producing fertilizers and machinery for agriculture and the embedded emissions in your bike, to the extent those are oil/gas/coal based.

[1] https://ecf.com/news-and-events/news/how-much-co2-does-cycli...

Re: Why Do Computers Use So Much Energy?

#130

Post by ajuc »

zaroth wrote: post #77
zwieback wrote: post #42

Earlier quoted context omitted.

So so true. Every time I go back to programming microcontrollers in C I'm amazed at how much can be done with just a little code. We waste so much on fluff. But then, we do enjoy the fluff.

Fluff in theory should equate to productivity. Sometimes we stop just a bit too soon. I’ve found a great rule of thumb is that once you’re code complete on a module, put in an extra 10% of work with the profiler to try to improve performance. Keep doing 10% spurts until the performance improvement of the last spurt is less than 5x. There’s almost always low hanging fruit which will return at least 10x. Sometimes you…

It helps to have performance targets. Like 60fps, sub-100ms ui reactions, no stuttering, throughput matters or not, timing attacks are a concern or not.

It's often the case that optimizing a special case 10 times increases throughput, but makes the user experience worse (because it starts stuttering), makes the code ugly, and allows for timing attacks. So, in many contexts it's actually bad idea.

Half the work in optimization is measuring the correct thing.

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