Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Single-chip processors have reached their limits

spectrum.ieee.org

Post reply on HN
Print view View original

111–120 of 159 posts

Re: Single-chip processors have reached their limits

#111

Post by ReactiveJelly »

AnthonyMouse wrote: post #92
bob1029 wrote: post #67

Despite the limitations apparently present in single chip/CPU systems, they can still provide an insane amount of performance if used properly. There are also many problems that are literally impossible to make faster or more correct than by simply running them on a single thread/processor/core/etc. There always will be forever and ever. This is not a "we lack the innovation" problem. It's an information-theoretic /…

The alternative is speculative execution. If you can guess what the result is going to be, you can proceed to the next calculation and you get there faster if it turns out you were right. If you have parallel processors, you can stop guessing and just proceed under both assumptions concurrently and throw out the result that was wrong when you find out which one it was. This is going to be less efficient, but if your…

Except that synchronizing two or more cores is, as a rule of thumb, too expensive to do per-instruction?

Re: Single-chip processors have reached their limits

#112

Post by ip26 »

paulmd wrote: post #93
ip26 wrote: post #51

Earlier quoted context omitted.

The other one big obstacle is chips are square while wafers are round.

it depends on the exact shape of your mask of course, but typically losses around the edges are in the 2-3% range. It's not really possible to fix this either since wafers need to be round for various manufacturing processes (spinning the wafer for coating or washing stages) and round obviously isn't a dense packing of the mask itself. It just kinda is how it is, square mask and round wafer means you lose a bit off t…

The interesting part is loss scales with the die size.

Re: Single-chip processors have reached their limits

#114

Post by jpmattia »

retrac wrote: post #6

The best chiplet interconnect may turn out to be no interconnect at all. Wafer scale integration [1] has come up periodically over the years. In short, just make a physically larger integrated circuit, potentially as large as the entire wafer -- like a foot across. As I understand it, there's no particular technical hurdle, and indeed the progress with self-healing and self-testing designs with redundancy to improve…

> Wafer scale integration [1] has come up periodically over the years.

Not merely years, but decades. I worked with a wafer-scale group in MIT Lincoln Laboratory back in the late 80s. I'd say there is a reason the technology hasn't taken off in the past 35 years, but who knows, maybe now is the time for wafer scale integration to shine.

Incidentally, that group was originally Ken Olsen's group, after he left to go found Digital Equipment Corporation (DEC). They had a lot of talent and produced some interesting wafers. The tech back then (4in wafers iirc) used laser reconfigurability to route around bad cells.

Re: Single-chip processors have reached their limits

#115

Post by chii »

AnthonyMouse wrote: post #99
tsimionescu wrote: post #98

Earlier quoted context omitted.

Not necessarily. There are problems you can't speed up even if you are given a literal infinity of processors - the problems in EXP for example (well, EXP - NP). Even for NP problems, the number of processors you need for a meaningful speed up grows proportionally to the size of the problem (assuming P!=NP).

Computational complexity and parallelism are orthogonal. Many EXP algorithms are embarrassingly parallel. You still have to do 2^n calculations, but if you have 1000 processors then it will take 1000 times less wall clock time because you're doing 1000 calculations at once. The reason parallelism doesn't "solve" EXP problems is that parallelism grows linearly against something whose time complexity grows exponentiall…

But what if the processor may be made organic, or encoded in DNA, so that replication and protein synthesis is akin to solving the problem? The "computer" grows exponentially, rather than linearly, and so for larger problems, it grows to the size that solves the problem?

Or we end up with grey goo...

Re: Single-chip processors have reached their limits

#116

Post by userbinator »

bob1029 wrote: post #67

Despite the limitations apparently present in single chip/CPU systems, they can still provide an insane amount of performance if used properly. There are also many problems that are literally impossible to make faster or more correct than by simply running them on a single thread/processor/core/etc. There always will be forever and ever. This is not a "we lack the innovation" problem. It's an information-theoretic /…

they can still provide an insane amount of performance if used properly.

In other words, software bloat has eaten up the bulk of the performance.

Re: Single-chip processors have reached their limits

#117

Post by jayd16 »

sliken wrote: post #56
2OEH8eoCRo0 wrote: post #16

Earlier quoted context omitted.

> The M1 Ultra is fabricated as a single chip. I'm curious how much the M1 Ultra costs. It's such a massive single piece of glass I'd guess it's $1,200+. If that's the case it doesn't make sense to compare the M1 Ultra to $500 CPUs from Intel and AMD.

Dunno, M1 Ultra includes a decent GPU, which the $500 CPUs from Intel and AMD do not. Seems relatively comparable to a $700 GPU (like a RTX 3070 if you can find one) depending on what you are using. Sadly metal native games are rare, many use some metal wrapper and/or Rosetta emulation. Seems pretty fair to compare an Intel alder lake or higher end AMD Ryzen AND a GPU (rtx 3070 or radeon 6800) to the M1 ultra, assumi…

What are you using to make the comparison to a 3070? Not close in any benchmarks I've come across.

Re: Single-chip processors have reached their limits

#118

Post by ksec »

narag wrote: post #103
ksec wrote: post #81

Earlier quoted context omitted.

>would it cost 100x to produce or just 10x or just 2x? Why would 100x something only cost 2x to produce? >what % of the costs is "physical cost per unit" and what % is maintaining the I+D, factories, channels...? Without unit volume and a definition of the first "cost" in the sentence no one could answer that question. But if you want to know the BOM cost of a chip, it is simply Wafer Price divided total useable chip…

Why would 100x something only cost 2x to produce? If you create an app, the cost is mostly developing it. Once you can sell a copy, you can sell 100x for more or less the same cost. It's tricky for physical things. We tend to think that costs correlates with weight or volume, but that's wrong. The price of a typical 100 ml (3.4 fl oz) perfume is around $50 in shops, for an "official" $100 price. The cost of the juice…

That is only in the case of software, where the unit cost does not increase since it is nearly zero. What you wrote about perfume and juice are not unit "cost", but "price". Unit Cost, or BOM or COGS does not include --> the perfumist, the bottle, the box, shop markup, distribution markup, marketing, tv commercials, design, samples...

I am assuming the "I" here stands for Initial Investment or CapEx. And in the context of Foundry Customer it is more like R&D since they dont invest in Machineries. The foundry does that aka Intel , TSM, Samsung. The R&D cost again is not a percentage of "price" or "cost" since there is not expected volume to divide in the first place. And it depends on the complexity of the chip as well as node. On Leading Edge node tooling becomes much more expensive. Expect the Cost of Entry to be $300M+ ( for 7nm, definitely higher now for 5nm and 3nm ) for tools excluding masks and other steps. Making a chip with 99.9% of SRAM would have near zero R&D cost except for the mask. Complexity of your chip and design would dictate how many mask required before your final production. However multiple SKUs ( or dies variation ) could shared the cost of mask which is in the double digit million per run.

And none of these includes packaging and testing.

R&D dominates the cost of chip once you factor in engineers cost, and hence you often see Qualcomm ( or any other Fabless Company ) chasing volume despite it is often not in their best interest in terms of margin.

And and none of these includes the cost of IP, to ARM, IMG, CEVA, Lattice etc or Patents. Most of these are also per unit based. And probably other things I cant record on top of my head right now.

Re: Single-chip processors have reached their limits

#119

Post by tgamblin »

bob1029 wrote: post #67

Despite the limitations apparently present in single chip/CPU systems, they can still provide an insane amount of performance if used properly. There are also many problems that are literally impossible to make faster or more correct than by simply running them on a single thread/processor/core/etc. There always will be forever and ever. This is not a "we lack the innovation" problem. It's an information-theoretic /…

All of this is true, but I’ll just be nitpicky to make a point:

> Does a future event's processing circumstances maybe depend on all events received up until now?

In a parallel prefix sum, the final sum does depend on all prior inputs, but a good parallel implementation runs in O(log(n)) time. It is, of course, not a total ordering problem, but that’s not obvious at first glance — I’ve always thought it was a beautiful example of something that appears to be entirely sequential but actually parallelizes really well.

All of which is to say that, yeah, we’re latency bound at the end of the day, but there’s a lot more innovation and performance left to be wrung out of most systems. A little creativity goes a long way, and I like the idea of a universe where the software is the main determinant of performance — where you can’t get away with just waiting for the next generation of chips.

Post reply on HN