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Why has CPU frequency ceased to grow? (2014)

software.intel.com

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Re: Why has CPU frequency ceased to grow? (2014)

#101

Post by kale »

pjc50 wrote: post #91
skrebbel wrote: post #79

Earlier quoted context omitted.

> Basically the message was that serial performance is saturating, and the only way to get speed improvements in the future is going to be by exploiting parallelism. People have been warning us about this for about 10 years now, but I still don't see those 64-core CPUs I was promised anywhere. If we had the amount of parallelism we were told we were going to get, we could give every app its own core. OSes could even…

If you can find an Nvidia GTX 1080, that has 2560 cores.

Without branching (or with limited branching, last I checked it masked and re-ran instead). A core implies both instruction and data operations, rather than SIMD behavior.

Re: Why has CPU frequency ceased to grow? (2014)

#102

Post by abpavel »

mysterypie wrote: post #80

The article doesn't answer the question at the fundamental level. The closest it gets is this: "Increased frequency depends heavily on the current level of technology and advances cannot move beyond these physical limitations." Certainly, Moore's law is just an observation and cannot go on forever. Would it fair to say that we've simply reached the point where we can no longer "keep up" with Moore's observation becau…

Indeed, that's what I looked for too. The current transistor gate pitch is approaching atomic sizes, which results in electrons leaking through by quantum tunneling. I was hoping to understand more about how speed of light and quantum behavior is preventing further progress. Article only mentions transistor switching speed.

Re: Why has CPU frequency ceased to grow? (2014)

#103

Post by Entalpi »

mjfl wrote: post #8

I took a class that went over this in depth like 3-4 years ago. Basically the message was that serial performance is saturating, and the only way to get speed improvements in the future is going to be by exploiting parallelism. However, most programmers, and programming languages, remain stuck in a serial-by-default paradigm. I'm surprised that there hasn't emerged a "parallel-by-default C++" kind of language + hardw…

X10 is kind what you are describing.

https://en.wikipedia.org/wiki/X10_(programming_language)

Re: Why has CPU frequency ceased to grow? (2014)

#104

Post by VHRanger »

quadcore wrote: post #10
mjfl wrote: post #8

I took a class that went over this in depth like 3-4 years ago. Basically the message was that serial performance is saturating, and the only way to get speed improvements in the future is going to be by exploiting parallelism. However, most programmers, and programming languages, remain stuck in a serial-by-default paradigm. I'm surprised that there hasn't emerged a "parallel-by-default C++" kind of language + hardw…

https://golang.org/ In case you dont know, Golang goroutines are a marvel of parallelism. They are coroutines which are dispatched on a few OS threads. So you can use 100% of a multi-cores CPU and yet, spawn, say, 10K of those light threads without worrying about context switches PLUS have them all run concurrently. I've found that golang is one of those rare language, like Lisp, that actually change the way you thin…

How is that an example an improvement over c++? C++ has had pragmatic omp parallel for for two decades

Re: Why has CPU frequency ceased to grow? (2014)

#105

Post by pjmlp »

kbart wrote: post #99
pjmlp wrote: post #81

Earlier quoted context omitted.

At least looking to their product sites, Microchip and Green Hills seem to have quite good tooling, then again I don't have embedded experience on modern systems, beyond mobile devices.

Do Microchip even produces multi-core MCU's? Haven't seen one, though I worked mostly with Cortex-A series so might miss something.

As I said, I don't have much experience in real embedded domain outside mobile devices (iOS, Android, UWP), but aren't Cortex-A5 supposed to handle up to 4 cores?

Re: Why has CPU frequency ceased to grow? (2014)

#106

Post by Sammi »

mysterypie wrote: post #80

The article doesn't answer the question at the fundamental level. The closest it gets is this: "Increased frequency depends heavily on the current level of technology and advances cannot move beyond these physical limitations." Certainly, Moore's law is just an observation and cannot go on forever. Would it fair to say that we've simply reached the point where we can no longer "keep up" with Moore's observation becau…

You're skipping over the main point of the article, which is that the reason it's hard to increase the clockrate is because it is dependent on the slowest instruction that can be done in one tick.

And the main method of making an instruction faster is by splitting it, but all instructions have now already been split as much as is possible, while still having them operate correctly.

Re: Why has CPU frequency ceased to grow? (2014)

#107

Post by Sammi »

abpavel wrote: post #102
mysterypie wrote: post #80

The article doesn't answer the question at the fundamental level. The closest it gets is this: "Increased frequency depends heavily on the current level of technology and advances cannot move beyond these physical limitations." Certainly, Moore's law is just an observation and cannot go on forever. Would it fair to say that we've simply reached the point where we can no longer "keep up" with Moore's observation becau…

Indeed, that's what I looked for too. The current transistor gate pitch is approaching atomic sizes, which results in electrons leaking through by quantum tunneling. I was hoping to understand more about how speed of light and quantum behavior is preventing further progress. Article only mentions transistor switching speed.

Because the subject of the article is explicitly about clock speed and not about making transistors smaller.

Re: Why has CPU frequency ceased to grow? (2014)

#108

Post by ztoben »

ilogik wrote: post #84
madez wrote: post #17

Earlier quoted context omitted.

While Rust doesn't promote a specific model for parallelism, it's stronger compiler helps a lot with that. https://doc.rust-lang.org/beta/nomicon/concurrency.html https://doc.rust-lang.org/book/second-edition/ch16-01-thread... I don't think fixing C(++) can give what Rust can give, because Rust has a clean start with these strong guarantees built-in while for C(++) it would always be an addon. Defaults are powerful.

Doesn't go also make it relatively easy to write parallel code?

I believe you're thinking of concurrency, which go handles pretty well with goroutines.

Re: Why has CPU frequency ceased to grow? (2014)

#109

Post by adwn »

pjc50 wrote: post #78
digi_owl wrote: post #69

Earlier quoted context omitted.

I can't shake the feel that this parallelism thing will be nothing but a wild goose chase, because nature seems to be highly serial in all but the most macroscopic of senses.

All of your cells and neurons operate in parallel.

And yet you only have a single train of thought [1] – or multiple interleaved trains, but that's concurrency, not parallelism.

[1] Plus a couple of background processes, like breathing, that execute in parallel.

Re: Why has CPU frequency ceased to grow? (2014)

#110

Post by monocasa »

pjc50 wrote: post #91
skrebbel wrote: post #79

Earlier quoted context omitted.

> Basically the message was that serial performance is saturating, and the only way to get speed improvements in the future is going to be by exploiting parallelism. People have been warning us about this for about 10 years now, but I still don't see those 64-core CPUs I was promised anywhere. If we had the amount of parallelism we were told we were going to get, we could give every app its own core. OSes could even…

If you can find an Nvidia GTX 1080, that has 2560 cores.

They're playing games with the term 'core'.

In CPU terms, a 1080 is 40 cores, each with a 64 way vector unit.

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