Fifty or Sixty Years of Processor Development for This?

It's almost certain one developer generates more CO2 than any reasonable number of servers that run their code. Anything that reduces manpower costs is a net positive for emissions. Besides, when the equation changes (say, when the software enters maintenance mode but the servers stay up), they'll be a strong economic incentive to spend the developer time to rewrite it more efficiently.

But think about this... how much CO2 would you spend getting developers to work every day so they can reduce CO2 somewhere else? I suspect the biggest users of DC power, in terms of code, are already written in languages like C++.

Also, regarding scale: the number of entities operating at AmaFaceGoog scale is small. The number of entities operating even within an order of magnitude or two of them is small. The odds are very much against any advice relevant only at that scale being relevant to the average Hacker News reader.

Why, I happen to have hacked on Lisp implementations. Including Thinlisp, which is a compiler for a non-garbage collected real time subset of Common Lisp. And what you say is still wrong.

An interpreter is not the same as a bytecode VM, and is not the same as native code compilation. And none of those things are a property of programming languages. The only programming languages where that might remotely be true are purely string-based ones like TRAC and maybe some of the term rewriting ones.

> even a property access or arithmetic operation may invoke an arbitrary, not-predictable-at-compile-time piece of code, and hence require runtime dispatch.)

If that's the criterion, then vtables make C++ "interpreted."

(That's not meant to be pejorative. Just saying I understand why companies would be loathe to ditch proven tooling w/ a lot of sunk costs).

From what I remember, the IBM System Z mainframes also do this sort of thing and have dedicated IO processors that can decode XML on the fly for you and other fun things like that.

My impression is that that the process of filtering DB rows is sufficiently complex to need a full libc type execution environment. But taking a big step back in perspective, a famous example of filtering on processors connected to disks is Map-Reduce, aka Hadoop.

> What if the network controller could evaluate your firewall rules itself, so dropped packets wouldn't have to interrupt the main CPU?

Yes, this is a real thing: https://duckduckgo.com/?q=nic+packet+filter+offload

The rumor is that integration of the cobalt material is what's causing yield issues at Intel for 10nm.

And in a world where we rely more and more on libraries, my ability to improve on a piece of code is greatly curtailed. Sending in the compiler to help might be my best option.

On smaller low power cpus it is more significant of course.

The stack engine is necessary anyway even if you have no specific stack instructions, as it removes the dependence of the top of stack manipulation from local variable accesses which is critical. Explicit stack manipulation instructions might actually make the stack engine simpler.

Coherent instruction cache and pipeline are super relevant in this age of pervasive self modifying code (a.k.a JIT).

Modern CPUs are complex for a reason.

None of the changes to x86 people have thought of over the years really helps enough to break backcompat. Simply because they aren't on the fast path on the critical execution stage. The limit imposed on frequency by power in current cpus is not really the total amount of power consumed, it's the amount of power consumed in the <0.25mm of chip that houses the register file, forwarding network and alus. That is, the place were things actually happen during the most important pipeline stage. This is why a 8-core cpu running just a single thread cannot make one of the cores consume as much power as all the 8 would if running 8 threads -- the register file of the running core would just melt, even if the total power would stay below chip limits.

x86 decoding is hairy and takes a long time and a lot of transistors. However, it is placed in it's own pipeline stages, that are ran parallel to the execute and only slow it down by making a branch miss a little more expensive. And the power is limited today by caching the decoded uops in their own cache, so during any tight loop, the decode hardware is idle and consumes no power. The same sort of goes for the stack engine -- as it runs early in the pipeline, it is basically a way to compress instructions a little that saves power by making code more compact when it is running, and does nothing when it is not used. Removing it would not really help, even if all code instantly changed to accommodate. Much of the rest of the ugly warts of the x86 architecture is handled in the time-honored CISC way: just punt it to microcode, performance be damned. Today, self-modifying code technically works, but you never want to do it because invalidating lines in the L1i has been implemented in the way that is the fastest and cheapest way to make the common case of code that does not modify itself. (And which has to exists even if you don't support self-modifying code, because there has to be some way of invalidating L1i entries.) Similarly, a lot of the CISC instructions that make more sense to implement as software routines (fpu sin/cos for example) are today just abandoned ucode routines that are slower than rolling your own.

This was a different time. At that time researchers tried to build clusters out of PS3s - because the speed advantages of the Cell made it worth and "regular" Cell clusters were much more expensive. Some years later GPGPU became feasible and one could forsee that it will become faster than the Cell, too, in near future - and at that time the same kind of researchers dropped their PS3 clusters and built GPGPU clusters. Don't tell me that particular in the beginning GPGPU was easier to program for than the Cell.

It was also the time when Apple switched to Intel CPUs. I know at that time IBM was also trying to sell the Cell to Apple, but Steve Jobs refused and decided for Intel instead.

This decision of Apple and the decisions of researchers to stop tinkering with PS3 clusters and build GPGPU clusters instead were in my opinion the two landslides after which the fate of the Cell was destinied.

Neither CPU nor GPU are progressing as fast as some predicted anymore.

Additionally the shift to consoles as stable hardware platforms over time has put a damper on computing power required by economically viable games.

The remaining outlets are VR and huge resolution (same thing actually) - and high quality and fidelity simulations. (Including AI.)

It's 3 year old tech whose performance/$ is still around $300 today and it struggles. Gotta turn those settings down with my r9 390 in every modern intensive game!

    The speed of electricity in a 12-gauge copper wire is
    299,792,458 meters per second x 0.951 or 285,102,627
    meters per second. This is about 280,000,000 meters
    per second which is not very much different from the
    speed of electromagnetic waves (light) in vacuum.

An attempt to produce entire wafers in one go is also a big gamble. Any defects in the manufacturing could ruin the entire wafer rather than individual chips. Parts of the wafer could be disabled if defective, but it would result in a combinatorial explosion of different configurations.

Also worth noting that in 1980 when Wafer Scale Integration was researched (without success), wafers were 4" diameter. Current wafers are 10-12" in size, which makes the process much more difficult and error prone.

There's also a ton of practical issues regarding the process. Photolithography equipment, cutting the wafers, the machines handling and packaging the chips. All would have to be redesigned and I'm sure that would cost more than the saved silicon during the lifetime of the whole plant.

The current chip sizes are already getting pretty close to hard limits (speed of light, etc). 900 mm^2 is 30 mm across, which is about half of the distance light travels in a clock cycle (async/clockless circuitry could help here).

Larger chips are also less efficient. A while ago I was discussing power efficiency with a HW designer working on memory controllers and he was using a fancy unit called "nanojoules per bit-millimeter", ie. how much energy it takes to flip a bit that is physically located a certain distance away. The efficiency gets much worse as distance increases.

Increasing wafer size also improves the yield, which is why Intel has an advantage with 12" wafers (others have 10").

Instead of creating larger chips, the current trend seems to be about packaging more chips in a single package and connecting them more efficiently. In particular, it's about bringing memory closer to the CPU to get those bit-millimeters down.

>A related approach is programmable asics. I've heard this was researched decades ago

What do you mean, if not fpgas?

[0] https://en.bitcoin.it/wiki/Mining_hardware_comparison https://en.bitcoin.it/wiki/Non-specialized_hardware_comparis...

because they aren't intended to run non-neural-net workloads. you don't judge a dishwasher by it's ability to wash your clothes, do you?

> Where does [the speed limit] come from?

Initial conditions. More on that in a moment.

> What enforces it?

We can parameterize c in our fundamental theories (or expansions thereof) and take a rigorous if mathematical approach to asking questions like: what if the (arbitrary) value of c were not constant everywhere -- for example, if it were different in the past of every point we can currently observer, or if it is different in one spacelike direction from another spacelike direction. We can also fix various sets of units and adjust c's arbitrary value up or down everywhere in spacetime. It turns out that astrophysical observables are highly sensitive to the universality of c, and that it would be virtually impossible for us to notice even a very small gradient in c since the very very early universe, and when we use just about any set of units to describe physics and then adjust the value of c in those units up or down we also get strongly different observables in astronomy and laboratory physics.

So, it's not so much that it's "enforced", but rather that a different value of c, or a non-universal value of c, is strongly constrained by physics achievable in Victorian-era laboratories or by modern amateur enthusiasts.

There are further types of "breaking" of the invariance of c, wherein one can have some fundamental interaction be constrained by a constant other than c. Most variable speed of light theories are directly written as (or clearly equivalent to) bimetric theories of gravitation, wherein some microscopic component of the Einstein Field Equation couples to a metric other than the standard one that everything else couples to.

A toy example would be some form of exotic matter moving superluminally in Schwarzschild blackhole spacetime, such that there is an "inner" horizon that affects this exotic matter, and at high energies an interaction between normal matter and this exotic matter that transfers information from the former to the latter between the two horizons, allowing that information to escape to infinity encoded in the exotic matter. There are other examples from cosmology designed to do away with some aspects of the observed universe that support Cosmic Inflation (e.g. some exotic matter couples to a metric that allows it to spread heat evenly across the very early universe faster than heat could propagate if constrained by "c").

Such examples again are highly constrained: in both cases the second metric has to decay away so as to avoid being readily detected by our modern instruments. In the cosmological case, it has to be gone well before primordial nucleosynthesis, or it would leave obvious fingerprints in the cosmic microwave background and in the distribution of galaxies on our sky; the BH toy requires at least a cutoff that depends on the mass of the black hole, and so suffers badly when trying to apply the "toy" to real astrophysical situations involving collapsing stars.

An anthropic argument answer is that the state of the universe around us humans is highly sensitive to conditions in our distant past, and thus our own existence is strong evidence supporting c as a constant everywhere in the past of the stuff that makes us human. Since that includes the views of objects in our sky as we make better and better telescopes, that [a] is further supporting evidence that [b] c is very likely a universal constant. Is that enforcement? That's probably more a metaphysical question than a physical one.

(We can tone down the anthropic argument a bit and ask for evidence for a statement like: if c takes on an experimental value in one point in a spacetime filled with fields like ours, it must take on the same value at every other point in that spacetime too).

Finally, "where does [the constant c and its value] come from": we don't know yet, but obviously there are scientists working in the subdisciplines listed in my first paragraph (and more) who are trying to find out. On the one hand, the parenthetical comment above suggests that we bend our own thinking and just accept that it doesn't "come from" anywhere, it just is; on the other hand we're pretty biased culturally with ideas about sequencing of cause and effect and about there being a real difference between past and future, so we like to slice up spacetimes into space and time and then think about how each space-like slice is related to its neighbours, and then to their respective neighbours, and so on. This cultural habit may be fruitful, or it may be a handicap, when it comes to answering questions about c. However, returning to "initial conditions", our present spacelike slice was determined by its immediate predecessor in the past, and that was determined by its immediate predecessor, and so on. If we keep regressing we might expect to come to "the start of time", and find some mechanism which sets c on that initial spacelike hypersurface.

However, there are lots of ways to avoid having such an initial spacelike hypersurface even in a big bang cosmology! So while "initial conditions" is culturally the most favoured answer, and is well supported by evidence from physical cosmology, that may not be a sufficiently full answer. And that's going to be a topic for scientific research for some years to come...

You have to admire us for trying our best tho :-)

This suggests that it's possible one day to have computers some orders of magnitude better. If you look at it from first principles, of course it's possible. The brain is unlikely to be the most efficient design of neural network allowable in this universe. So given enough time, we'll learn how to build it better.

Then it's just a manufacturing and energy problem to match the number of human minds on the planet. So no, I don't think it's impossible at all.

Just ridiculously freaking hard, and not likely to happen in our lifetimes.

When the evolution of intelligence goes beyond the stage of slowly evolving (if evolving at all) forms like humans, "life" will spread like a plague through the universe and its only purpose will be to convert all matter into "shit that can run the software that is we"... Any intelligence with a different purpose will simply be eaten alive but those with this one.

Only the second law of thermodynamics can stop that, and even that only "works" the way we imagine in a finite universe (and despite out forced rationalization and intellectual masturbations our brightest were capable of, we have no reason to believe anything is anything but infinitely infinite, whatever that could even mean). And we can't even imagine how the evolution of information in infinite space and time could unfold, even with "local containment" via the "light speed limit"...

An no, we are not unlikely to model anything such complicated, we are almost sure not to... Because "the children" will awake much sooner that this computational power will exist, probably doing the right thing of terminating bio-humanity as it's so (computationally) wasteful, and remnants of us will only endure in "historical entertainment simulations" thinggies... (And this is the optimistic scenario anyway, in which post-human life would retain some human-type characteristics by virtue of "descending" from us. If an alien superintelligence reaches Earth first it might not even care to analyze us well before restructuring matter for its own purpose, so paradoxically, developing superhuman-intelligence-that-will-terminate-bio-humans asap is probably "humanity's best bet" of "not being completely forgotten" / "transmitting our memes".)

EDIT: Also who says that time inside the simulation has to run the same rate as real time?