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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?

#31

Post by collyw »

bottled_poe wrote: post #29
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.

I'm not really sure how that puts things into perspective. I actually have no concept of how fast photons are whizzing around the room.

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

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

#32

Post by collyw »

userbinator wrote: post #16
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.

No, I don't think the things most people do with computers should require any faster hardware; the problem is that software is often being written to require increasingly more resources under the false assumption that processing speed and memory are "infinite" or close to it. The exponential growth that started many decades ago has promoted a culture of extreme waste. From the earliest notions of "premature optimisat…

>The exponential growth that started many decades ago has promoted a culture of extreme waste.

In fairness, I look back at what I was working on ten years ago, and I am currently writing my companies database and web front end, on my own, thanks to the layers of abstractions (scripting language, web framework, improvements in database technology). This database is able to do more than what a team of 5 could accomplish ten years ago. You can't deny that sort of efficiency is not beneficial to many (most?) organisations.

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

#33

Post by badsock »

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

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

#34

Post by ownagefool »

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…

This would be because, given the workload, your external drive isn't quick enough to keep up with the CPU while your internal is?

You could obviously use something like nice / ionice if you don't want to kludge an external drive about, but to me it seems like an inherit problem with our systems that we can make them unusable just by doing something like a compile.

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

#35

Post by Artemis2 »

collyw wrote: post #31
bottled_poe wrote: post #29

Earlier quoted context omitted.

I'm not really sure how that puts things into perspective. I actually have no concept of how fast photons are whizzing around the room.

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 years ago, our beat creations were basically piles of rock.

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

#36

Post by agumonkey »

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 can leave happily with a core2duo. The bottlenecks are memory and hdd (ssd fixing 80% of that). Except for HD, games and non-mainstream tasks (compiling large software, video transcoding) that is.

People are right, it's a systemic issue now, we need to rearchitect things and avoid inefficiencies (lock free research, persistent data structure, programming paradigms [go, erlang...]). I may be wrong but unless you're using gentoo (and even then) your software will never use hardware to its fullest.

The main reason I want a recent processor : power consumption. Having a 5W fanless piece of silicon is the main advantage over my old one.

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

#38

Post by getsaf »

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.

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

#39

Post by claudius »

collyw wrote: post #32
userbinator wrote: post #16

Earlier quoted context omitted.

No, I don't think the things most people do with computers should require any faster hardware; the problem is that software is often being written to require increasingly more resources under the false assumption that processing speed and memory are "infinite" or close to it. The exponential growth that started many decades ago has promoted a culture of extreme waste. From the earliest notions of "premature optimisat…

>The exponential growth that started many decades ago has promoted a culture of extreme waste. In fairness, I look back at what I was working on ten years ago, and I am currently writing my companies database and web front end, on my own, thanks to the layers of abstractions (scripting language, web framework, improvements in database technology). This database is able to do more than what a team of 5 could accomplis…

It depends. For in-house software, I can fully understand that wasting a few developer hours less may well be enough to justify buying beefier CPUs for the couple of users who need them.

On the other hand, if thousands of people need better CPUs to load imgur comments (e.g.) instantaneously instead of forcing the browser to a grinding halt for a task that should be essentially trivial, things may look different.

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

#40

Post by s_dev »

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.

I think it's a great way to put it in perspective for me at least, light is the fastest thing in the universe it's the ultimate constant for reference. We could measure computation in light-cycles similarly as we do with lightyears for really long distances. I don't get frequencies like I do distances, I think it's because I deal with distances all the time but less so with frequencies.
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