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Are processors pushing up against the limits of physics?

arstechnica.com

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Re: Are processors pushing up against the limits of physics?

#41

Post by runeks »

tedsanders wrote: post #3

Right now, the laws of economics are a bigger problem than the laws of physics. Field effect transistors have been shown to work 5nm and even 3nm. However, the new lithography technologies needed to reach those resolutions cheaply are nowhere near ready.

> Right now, the laws of economics are a bigger problem than the laws of physics.

The "laws of economics" and the "law of physics" are two sides of the same coin in this case.

It's the laws of physics that prevents us from producing arbitrarily cheap chips, it's not two separate factors.

The "laws of physics" are our hurdles, and the more we pass the cheaper the chips get.

Re: Are processors pushing up against the limits of physics?

#42

Post by readerrrr »

Artemis2 wrote: post #35
collyw wrote: post #31

Earlier quoted context omitted.

Takes light 8 minutes to get from the sun to here. (To put it in perspective.)

That's effectively how I see it: as a simple human, I consider light as an instantaneous phenomenon. Its speed seems to be the maximum attainable for about anything, but a man-made processor has the power to execute a simple computation in less time than what it takes for light to travel 9 centimeters. Isn't that impressive? Doesn't that cast doubt on how far we can improve our CPUs? Just remember that a thousand yea…

Pyramids, built over 4 millennium ago, a marvel of accuracy and the highest man made object until the year 1300, would beg to differ.

Unbelievable:

The pyramid remained the tallest man-made structure in the world for over 3,800 years,[8] unsurpassed until the 160-metre-tall (520 ft) spire of Lincoln Cathedral was completed c. 1300. The accuracy of the pyramid's workmanship is such that the four sides of the base have an average error of only 58 millimetres in length.[9] The base is horizontal and flat to within ±15 mm (0.6 in).[10] The sides of the square base are closely aligned to the four cardinal compass points (within four minutes of arc)[11] based on true north, not magnetic north,[12] and the finished base was squared to a mean corner error of only 12 seconds of arc.[13] The completed design dimensions, as suggested by Petrie's survey and subsequent studies, are estimated to have originally been 280 Royal cubits high by 440 Royal cubits long at each of the four sides of its base. The ratio of the perimeter to height of 1760/280 Royal cubits equates to 2π to an accuracy of better than 0.05% (corresponding to the well-known approximation of π as 22/7).

Re: Are processors pushing up against the limits of physics?

#43

Post by grondilu »

In June of this year HP announced its plan to build "The Machine". Regardless on how feasible their project is, I think they are right in pointing out that memory is the current bottleneck in computer engineering. We don't need faster processors. Focusing on the size of transistors, which are already insanely small when you think about it, may be a mistake.

Re: Are processors pushing up against the limits of physics?

#44

Post by vanderZwan »

getsaf wrote: post #38
Artemis2 wrote: post #4

A metric that really puts things in perspective is the following: take a common consumer CPU, clocked at 3.4Ghz. That means it executes 3,400,000,000 cycles per second. Divide the speed of light by this number, and you obtain approximatively 0,088m. During the time your standard desktop CPU takes to finish a cycle, light only travels 9 centimeters.

Not much perspective to be had here unless you are assuming a single photon's distance traveled. The analogy breaks down when you consider thousands or millions/billions of photons traveling simultaneously, then you can measure in miles. A single photon's travel-distance doesn't mean much in this context.

As far as I know, those 9 centimetres are still the fundamental speed limit for information to travel.

Re: Are processors pushing up against the limits of physics?

#45

Post by ehsanu1 »

gizmo686 wrote: post #28
DiabloD3 wrote: post #13

The question I want to ask is, are generic CPUs now fast enough that people no longer need faster CPUs? I have an i7-4771 on my desktop (bought instead of 4770K because I wanted TSX... thanks Intel ;), and I can't really imagine much use for an even faster CPU unless I'm gaming or doing heavy compute work.

I think gaming is still the big issue. I have an i7-4800MQ and frequently do large compiles. At first, my computer became almost unusable during compiles, which I attributed to the CPU being hogged by the compiler. I recently switched to doing my builds on an external hard-drive and no longer notice any performance difference when I am compiling. I don't remember the last time I have seen my CPU running near 100% (ot…

My guess is that you were swapping. In addition to slowness, this explains how switching to an external hard drive for the files you're compiling would help, since it would reduce contention on a single hard drive.

Next time it happens, check if you're out of memory and using a lot of swap space/virtual memory. If so, you just need more RAM. Also, the best upgrade for any computer these days is an SSD, an HDD being the slowest part of modern computers.

Re: Are processors pushing up against the limits of physics?

#46

Post by Artemis2 »

vanderZwan wrote: post #44
getsaf wrote: post #38

Earlier quoted context omitted.

Not much perspective to be had here unless you are assuming a single photon's distance traveled. The analogy breaks down when you consider thousands or millions/billions of photons traveling simultaneously, then you can measure in miles. A single photon's travel-distance doesn't mean much in this context.

As far as I know, those 9 centimetres are still the fundamental speed limit for information to travel.

That's really what makes me fear about how far we can push our processors. I don't think Moore's law will hold a lot longer for CPUs, unless we manage to get very good quantum computers very soon.

Re: Are processors pushing up against the limits of physics?

#47

Post by tsotha »

badsock wrote: post #33
tsotha wrote: post #26

Depends on exactly what you mean. You can keep adding cores until the cows come home. And I don't really buy the "we don't know how to use all those extra cores" argument. Multi-threaded code isn't the rocket science it's portrayed to be in the press. One thing that may become practical is die stacking, depending on what they can do about extra heat.

Amdahl's law is a SOB: http://en.wikipedia.org/wiki/Amdahl%27s_law

Except that's not how multiple cores are normally used.
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