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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?

#71

Post by gnulinux »

gameswithgo wrote: post #20
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…

You could probably cut that consumption in half if people stopped using interpreted languages in production, quit telling curious young programmers that early optimization is evil or that memory is an implementation detail, etc. etc. The computer is very efficient, electrical engineers toil and sweat a great deal to make them so. Then we build things with Ruby and Python and make things 2 orders of magnitude less eff…

> no good reason

It's a trade-off. You can compute everything in C, or some things in python. In the former scenario you're trading off software engineering cost with computational efficiency. Since software engineering is insaaaaaanely expensive (I code stupid stuff all day and am paid $150k/y) and processors are dirt cheap compared to them, it makes a lot of sense to do some computing in python/ruby/javascript.

Re: Why Do Computers Use So Much Energy?

#72

Post by kens »

blattimwind wrote: post #6
pizzakiller85 wrote: post #2

What i don't understand is how a phone can be so powerful with so little watt usage. especially compared to a PC

Power consumption is more or less square to per-thread throughput. Power consumption is between square and m^n to inter-core bandwidth and count. So, a high-end smartphone CPU might do 1/5th of the throughput of a desktop CPU using 1/25th of the power.

Those formulas seem highly unlikely to me. Power consumption is generally proportional to clock speed. And I don't know what m^n even means in this context.

Re: Why Do Computers Use So Much Energy?

#73

Post by deathanatos »

gvb wrote: post #22
pizzakiller85 wrote: post #2

What i don't understand is how a phone can be so powerful with so little watt usage. especially compared to a PC

1) Your phone is mostly sleeping (extremely low power state). Your laptop also uses very little power when sleeping. That is why your laptop can sleep for a week++ but can only run for 3-8 hours. 2) Your phone is not nearly as powerful as your laptop despite similar specifications of the CPU speeds. Pretty much everything other than the base CPU clock rate is much, much slower. In addition, your phone CPU down-clocks…

Sounds a bit like "Progressive Performance (Chrome Dev Summit 2016)": https://www.youtube.com/watch?v=4bZvq3nodf4

Re: Why Do Computers Use So Much Energy?

#74

Post by noir_lord »

orev wrote: post #66
flyGuyOnTheSly wrote: post #54

Earlier quoted context omitted.

My thoughts exactly. When reading the title I thought "They do?" My laptop consumes the equivalent of approximately a single 60w incandescent lightbulb that used to be required just to write on a pad of paper in the dark. It's capable of quite a bit more than that, however. EDIT: Updated power specifications to exact amounts.

If your laptop consumed that much power it would be too hot to use on your lap and also would probably damage whatever surface you put it on. Just because a power supply has a max rating of X Watts doesn’t mean it’s always using that much. Even then, 200w for a laptop is an enormous amount. Maybe you meant LED bulbs that emit the equivalent light of a 100w bulb? That would be much closer to standard laptop power cons…

Indeed.

I have a Thinkpad that has an i7-7700HQ, that's a 35W TDP beast and even under very heavy load I still get 90 minutes out of a 72 watt-hour battery and it gets pretty warm (and the TP has excellent cooling), 200W would melt your legs.

Re: Why Do Computers Use So Much Energy?

#75

Post by rectangletangle »

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…

I would be surprised if the 5% that goes toward computing didn't knock down transportation from 35% to 30% through improved logistics alone. My gut feeling is computers are a net positive energy wise.

Also what percentage of that 5% goes to mining bitcoin, or re-downloading jQuery for the 5000th time?

Re: Why Do Computers Use So Much Energy?

#76

Post by mikeash »

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…

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.

Re: Why Do Computers Use So Much Energy?

#77

Post by zaroth »

zwieback wrote: post #42
NickM wrote: post #31

Earlier quoted context omitted.

Phones are much less powerful than PCs, but they feel comparably fast because most software developers waste exactly as much performance as they can get away with. The phone app developers are forced to write better, faster code than the PC app developers, just as PC app developers ten years ago were forced to write better code than PC app developers are today.

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 find multiple places where you get 10x and your code ends up more than 100x faster.

And at that point all your unit tests are written and green so the refactoring is pretty quick. Right? ;-)

Re: Why Do Computers Use So Much Energy?

#78

Post by gvb »

deathanatos wrote: post #73
gvb wrote: post #22

Earlier quoted context omitted.

1) Your phone is mostly sleeping (extremely low power state). Your laptop also uses very little power when sleeping. That is why your laptop can sleep for a week++ but can only run for 3-8 hours. 2) Your phone is not nearly as powerful as your laptop despite similar specifications of the CPU speeds. Pretty much everything other than the base CPU clock rate is much, much slower. In addition, your phone CPU down-clocks…

Sounds a bit like "Progressive Performance (Chrome Dev Summit 2016)": https://www.youtube.com/watch?v=4bZvq3nodf4

Yes, thanks!

Where he talks about benchmarked speed vs. marketing numbers: https://youtu.be/4bZvq3nodf4?t=676

Re: Why Do Computers Use So Much Energy?

#79

Post by metalliqaz »

mikeash wrote: post #76
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…

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.

That really depends on how you define "powerful". The computers are less capable in several areas, but also more capable by several orders of magnitude in other areas.

Re: Why Do Computers Use So Much Energy?

#80

Post by p1esk »

mikeash wrote: post #76
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…

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.

You can’t say it’s less powerful, it’s just different. It’s better at some things, worse at others, mostly because of the software.
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