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A New Golden Age for Computer Architecture

cacm.acm.org

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Re: A New Golden Age for Computer Architecture

#61

Post by Symmetry »

ansible wrote: post #60
Symmetry wrote: post #37

Earlier quoted context omitted.

I'm somewhat comforted by the fact that there are fundamental physical limits to computational efficiency[1] which we aren't at yet. MOSFETs look to be just about played out but there are tons of other potential computational substrates. Carbon nanotube transistors, photonics, nano-rod logic, magnetic coupling, DNA computing, etc. We're in for a big interregnum before we get a new paradigm working better than our exi…

All of the techs you have mentioned are potentially great, but none are close to ready for widescale production.

Right, I'm expecting a decade long interregnum at the least.

Re: A New Golden Age for Computer Architecture

#62

Post by ansible »

naasking wrote: post #45
ansible wrote: post #21

Earlier quoted context omitted.

Reaching "the end of Moore's Law" is a super big deal, and I still don't understand why people aren't worried about it more in general. It will cause a crash in the entire tech industry, which will throw the global economy into a depression.

> It will cause a crash in the entire tech industry, which will throw the global economy into a depression. Why?

The valuation of all the tech companies is based on future growth. Meaning ever increasing sales.

Well, what happens when next year's smartphone really isn't any better or cheaper than last year's smartphone? Sure, there will always be some business because people drop their phones all the time, but sales won't be as high without upgrades driving it.

Lots of people (investors) will be unhappy with the tech sector at that point.

Re: A New Golden Age for Computer Architecture

#63

Post by Taniwha »

gpderetta wrote: post #33
ghaff wrote: post #23

Earlier quoted context omitted.

I assume they’re counting them as RISC cores plus microcode that makes them compatible with older x86 CISC designs. Modern x86 is RISC under the covers by any meaningful definition-/and also shares pretty much all the problems.

x86 is not RISC by any meaningful definition. RISC vs CISC has always been about architecture, not microarchitecture. Breaking down instructions into microinstructions is as almost as old as the CPU itself and predates the CISC/RISC nomenclature by decades.

Compared to other CISC CPUs designed at the same time as x86s (Vax, 68k, 32k, etc) x86s ARE positively RISCy - the instruction set (with 1 or two minor exceptions - push) only has instructions with 1 memory address making exceptions/restart (paging code) simple and making instructions easy to break into simple uOps (one trip to the TLB for protection checking - Vaxes used to potentially do 27 and guaranteeing that instructions could make progress in all situations was problematical)

Re: A New Golden Age for Computer Architecture

#64

Post by Symmetry »

ranchpredictor wrote: post #4

Alot of what they suggest seem to be better solved in the domain of compilers and microcode translation on the fly.

Quite possibly! Or maybe at install or link time. Or maybe we're looking at a future where almost all code goes through a JIT engine and you've only got a few normal cores that run the OS that manages everything. Or possible everything will be Javascript[1].

[1]https://www.destroyallsoftware.com/talks/the-birth-and-death....

Re: A New Golden Age for Computer Architecture

#65

Post by ip26 »

Symmetry wrote: post #35
simula67 wrote: post #8

> Today, 99% of 32-bit and 64-bit processors are RISC > Concluding this historical review, we can say the marketplace settled the RISC-CISC debate; CISC won the later stages of the PC era, but RISC is winning the post-PC era It is clear that his assessment is right, but isn't the 99% number too high ? Servers, laptops and desktops still run x86 and they are CISC ( unless you are counting x86 as RISC based on microcod…

There's an x86 processor in your desktop, but there are many more RISC processors doing things like controlling your hard drive. If you buy an AMD processors there's even an ARM core inside the x86 processor in the Platform Security Processor. Add in all the microwaves, routers, the many processors in your car, and so on and 99% seems a bit high to me but not unreasonable.

Seems disingenuous though, as the two markets have totally different optimization points and volumes. More like RISC has won the low-cost, low-power market, and CISC-RISC hybrids won the performance market, or something like that.

I'm sure you can think of a million other markets like this- sedans vs race cars, fighter jets vs puddle jumpers, etc.

Re: A New Golden Age for Computer Architecture

#66

Post by Const-me »

ghaff wrote: post #23
simula67 wrote: post #8

> Today, 99% of 32-bit and 64-bit processors are RISC > Concluding this historical review, we can say the marketplace settled the RISC-CISC debate; CISC won the later stages of the PC era, but RISC is winning the post-PC era It is clear that his assessment is right, but isn't the 99% number too high ? Servers, laptops and desktops still run x86 and they are CISC ( unless you are counting x86 as RISC based on microcod…

I assume they’re counting them as RISC cores plus microcode that makes them compatible with older x86 CISC designs. Modern x86 is RISC under the covers by any meaningful definition-/and also shares pretty much all the problems.

Modern x86 is not RISC under the covers.

There’re instructions combining a dozen of math operations and also RAM loads, that on modern CPUs decode into just a single micro-op.

Example: https://www.felixcloutier.com/x86/vfmadd132ps:vfmadd213ps:vf... The AVX version computes x=a*b+pointer[i], for 8 independent SIMD lanes.

If you call that amount of stuff in a single micro-op “reduced instruction set” I wonder what exactly is the meaningful definition that you referred to?

Re: A New Golden Age for Computer Architecture

#67

Post by pulse7 »

3chelon wrote: post #22
simula67 wrote: post #8

> Today, 99% of 32-bit and 64-bit processors are RISC > Concluding this historical review, we can say the marketplace settled the RISC-CISC debate; CISC won the later stages of the PC era, but RISC is winning the post-PC era It is clear that his assessment is right, but isn't the 99% number too high ? Servers, laptops and desktops still run x86 and they are CISC ( unless you are counting x86 as RISC based on microcod…

The article specifically points out that Intel/AMD took on board all the lessons from RISC as they evolved the x86 series and now it's pretty much a RISC architecture too.

Most RISC architectures have fixed-length instructions (16-bit, 32-bit, 64-bit, 128-bit), whereby most CISC instructions are variable size. So x86 is not a RISC architecture...

Re: A New Golden Age for Computer Architecture

#68

Post by ddingus »

Reading this, I had a flash of a question:

RISC makes a lot of sense given compilers and many other possible optimizations?

However, there are increasing trends to put functions right into silicon too. Those frequently replace many instructions.

Will ML tech somehow make better sense of those things, and CISC in general?

Re: A New Golden Age for Computer Architecture

#69

Post by vanderZwan »

> As the architects of the Motorola 68000 and iAPX-432 both learned, the marketplace is rarely patient.

I hope this won't mean the Mill has no chance of success, or at least influencing the industry for the better. Every video seems to introduce interesting new ideas, or new takes on old ideas[0].

https://millcomputing.com/

Re: A New Golden Age for Computer Architecture

#70

Post by Symmetry »

ip26 wrote: post #65
Symmetry wrote: post #35

Earlier quoted context omitted.

There's an x86 processor in your desktop, but there are many more RISC processors doing things like controlling your hard drive. If you buy an AMD processors there's even an ARM core inside the x86 processor in the Platform Security Processor. Add in all the microwaves, routers, the many processors in your car, and so on and 99% seems a bit high to me but not unreasonable.

Seems disingenuous though, as the two markets have totally different optimization points and volumes. More like RISC has won the low-cost, low-power market, and CISC-RISC hybrids won the performance market, or something like that. I'm sure you can think of a million other markets like this- sedans vs race cars, fighter jets vs puddle jumpers, etc.

It's really a lot more than two markets. The high end communications systems that use MIPS have almost as high performance demands as a desktop or server. And currently the highest performance core is a POWER 9. But on the other hand you have a few places where x86 Atoms have made inroads as embedded cores, as in the UR robot arms I work with.

But really I think we really do overemphasize the importance of x86 because that's the architectures we have the most experience working with directly.

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