
A New Golden Age for Computer Architecture - matt_d
https://cacm.acm.org/magazines/2019/2/234352-a-new-golden-age-for-computer-architecture/fulltext
======
simula67
> 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 microcode )

> Many researchers assume they must stop short because fabricating chips is
> unaffordable. When designs are small, they are surprisingly inexpensive.

> High-level, domain-specific languages and architectures, freeing architects
> from the chains of proprietary instruction sets, along with demand from the
> public for improved security, will usher in a new golden age for computer
> architects. Aided by open source ecosystems, agilely developed chips will
> convincingly demonstrate advances and thereby accelerate commercial
> adoption.

It will be interesting if manufacturing also gets open sourced. There already
seems to be a project attempting this :
[http://libresilicon.com/](http://libresilicon.com/)

~~~
ghaff
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.

~~~
imtringued
I don't know why this gets thrown around but it's completely wrong. RISC and
CISC are about instruction set architecture. As soon as you have crossed the
decoder boundary you are deep into micro architecture territory where the ISA
is completely irrelevant because you can use the same techniques regardless of
whether you have RISC or CISC.

Now if one would take what you said at face value then it would actually imply
that RISC as an ISA is completely irrelevant because it is possible to achieve
the same benefits or even beat it despite CISC having the inefficiency of hard
to decode instructions and the high cost of a conversion step in the micro
architecture. One suddenly realizes that this battle of ISAs is completely
futile and the secret sauce is in the micro architecture which is completely
divorced from the ISA.

Here are some examples: ARM makes slow ARM chips. Apple makes fast ARM chips.
AMD made slow x86 chips in the past but now adopted a faster micro
architecture. Intel made Itanium but the chips didn't have any sort of dynamic
scheduling so they couldn't deliver the promised performance gains.

~~~
deepnotderp
Well, both Hennessy and Patterson have perpetuated the micro code and RISC
myth, presumably because it suits the "RISC world domination" narrative.

------
insulanian
I remember being excited about The Machine [1] from HP:

"The Machine will be a complete replacement for current computer system
architectures. There will be a new operating system, a new type of memory
(memristors), and super-fast buses/peripheral interconnects (photonics)."

"HP says it will commercialize The Machine within a few years, “or fall on its
face trying.”"

It seems later happened...

[1] [https://www.extremetech.com/extreme/184165-hp-bets-it-all-
on...](https://www.extremetech.com/extreme/184165-hp-bets-it-all-on-the-
machine-a-new-computer-architecture-based-on-memristors-and-silicon-photonics)

~~~
DJBunnies
Later always happens.

~~~
insulanian
Sorry for the typo :)

------
ChucklesNorris
I think back to the old Cat Stevens song "I Want To Live In A Wigwam", except
now I think maybe one day I'd like to live in a Faraday cage.

Computers, like guns, drugs, and any other invention of man are not inherently
evil. All these things can be used for good or evil. Unfortunately, the fly in
the ointment is human nature. With the convergence of cheaper but increased
computing power and the monetization of personal information, I fear what the
future holds. I hope I'm wrong, but it looks to me that humanity is doomed to
forever live in a state total surveillance and control. We're seeing it
happening already. Just the other day I saw an article that said that Sweden
is going to tax people on the miles they drive. The very next day I saw
another article saying Los Angeles is planning to do the same thing.

Sigh... I'm glad I'm old.

~~~
robin_reala
Every country already taxes people on the miles they drive, as every country
has a fuel tax.

~~~
ChucklesNorris
The difference is pay at the pump or pay via what your car's embedded GPS is
reporting. GPS also allows them to know when and where you were speeding, and
since Sweden went cashless, they can simply deduct the fines from your bank
account. Compliance is irrelevant.

If having a GPS device on your person becomes law, then avoiding the tax by
riding a bicycle, walking, riding a horse etc is defeated.

~~~
robin_reala
Could you link through to the article you read this in, because I live in
Sweden, own a car, and have not heard or seen anything about this.

------
4thaccount
I'm trying to think of what are some neat computer architectures out there.

Chuck Moore's "Green Arrays" is kinda cool and so is the Parallela board.

~~~
mpweiher
Transputer. Hardware multitasking and link-communication and a very compact
instruction set.

[https://en.wikipedia.org/wiki/Transputer](https://en.wikipedia.org/wiki/Transputer)

[https://en.wikipedia.org/wiki/XCore_Architecture](https://en.wikipedia.org/wiki/XCore_Architecture)

SOAR (Smalltalk On A RISC), though the conclusion there was mostly that a
plain old RISC will do. I wonder if that is still true today.

Rekursiv OO computer
[https://en.wikipedia.org/wiki/Rekursiv](https://en.wikipedia.org/wiki/Rekursiv)

NEC dataflow processor.
[https://books.google.de/books?id=qRrlBwAAQBAJ&pg=PA152&lpg=P...](https://books.google.de/books?id=qRrlBwAAQBAJ&pg=PA152&lpg=PA152&dq=NEC+7281&source=bl&ots=eI51Z6P4Ao&sig=ACfU3U0sFs_dluKsnjoORUk5RHGVX1UytQ&hl=en&sa=X&ved=2ahUKEwiDm8mv2ZLgAhUN3qQKHQHgBqQQ6AEwCXoECAIQAQ#v=onepage&q=NEC%207281&f=false)

~~~
4thaccount
Never heard of SOAR. It would be pretty sweet though to have a powerful &
multi-core chip running a Smalltalk OS that could do something with all the
cores. I'd also like to see kOS from Arthur Whitney if he ever finishes it,
although I'd never be able to afford any of their products.

~~~
mpweiher
[https://www2.eecs.berkeley.edu/Pubs/TechRpts/1986/CSD-86-287...](https://www2.eecs.berkeley.edu/Pubs/TechRpts/1986/CSD-86-287.pdf)

[https://www.deepdyve.com/lp/association-for-computing-
machin...](https://www.deepdyve.com/lp/association-for-computing-
machinery/soar-smalltalk-without-bytecodes-dMyiYUWgIr)

[http://digitalassets.lib.berkeley.edu/techreports/ucb/text/E...](http://digitalassets.lib.berkeley.edu/techreports/ucb/text/ERL-85-48.pdf)

Looking at the results, they say that hardware tag-checking for integer
arithmetic and register windows for fast method calls were the two most
important features of the design, nearly doubling performance.

I wonder if that still holds today, with the memory wall so dominant that CPUs
tend to be stalled quite a bit (therefore enough time to do tag checking in
software).

~~~
jabl
Nowadays the thinking seems to be that register windows were a mistake (e.g.
in SPARC), and newer designs such as RISC-V or Aarch64 don't do it.

------
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/](https://millcomputing.com/)

------
gbrown_
I'd hardly call this a "Golden Age", precisely because of the shortcomings
mentioned in the article. Regardless of how you may re-architect a processor
you will still end up hitting CMOS limitations in time.

To contrast my _fantasy_ for "Golden Age" would be multiple viable
replacements for CMOS that were actively being used in a variety of
processors.

~~~
pjc50
What specifically is "wrong" with CMOS? Not small enough for you yet? :)

~~~
ansible
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.

~~~
wibble10
How will reaching the end of Moore’s law cause a crash like this?

Do you mean that future requirements will outstrip capacity? I don’t think
this has been true for some time, we run a lot more systems and tend to scale
horizontally; doubling compute power every n period isn’t a hard requirement
imo.

~~~
imtringued
If we ever have an industrial revolution or massive productivity gains again
it will most likely involve autonomous machines for things like farming,
construction, delivery, transport, etc. All of these things depend on
increases in power efficiency or performance. It is possible that we are one
or two "doublings" away from achieving this in a mobile package and then
suddenly moore's law stops.

For example Tesla is betting on conventional cameras and tries to overcome
their shortcomings with computationally intensive machine vision. Tesla's
custom chips allows them to have more processing power which means they can
install more high resolution cameras and other sensors.

------
cbkeller
Interesting article with a lot of great historical context. I think a
significant part of the tl;dr is that the end of Dennard Scaling and trouble
with Moore's law may mean that the best architecture will finally win out,
rather than just the one with the best semiconductor design team behind it.

I'm a bit skeptical of the promise of DSAs, though it does seem we're already
going that way. Curious what others think on that point.

~~~
gbrown_
I agree, my concern is where do DSAs go in a few generations? How many
efficiency/performance gains can be had before hitting the same limits
hampering general purpose processors today?

~~~
Symmetry
A DSA is only going to be an order of magnitude or two more performant than a
general computer on any given process node. They'll certainly slow down at the
same time general purpose CPUs slow down. The thing is it makes more sense to
design and include them in a world where transistors are potentially getting
cheaper without getting better because a finite amount of engineering effort
will be stretched across a longer timeframe.

~~~
vanderZwan
Does that also imply a potential _power savings_ of an order of magnitude or
two? Because then it becomes a lot more obvious that the demand for them will
be there in mobile phones and laptops at least.

~~~
Symmetry
Yes, it does. And that's a big part of the push for dedicated co-processors
that we've seen in SoCs.

------
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?

------
Antonio123123
>Using parallel loops running on many cores yields a factor of approximately
7.

That depends on the number of cores.

------
rblion
It really is a fascinating time to be alive and aware.

The power of computing is redefining civilization, humanity.

------
deadpool007
I am getting application error while opening the link. Anybody facing the same
issue?

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

~~~
robin_reala
– As announced by Intel on the launch of the new Itanium architecture.

~~~
shifto
oh snap

~~~
ranchpredictor
_Slow clap_

