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David Patterson Says It’s Time for New Computer Architectures and Languages

spectrum.ieee.org

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Re: David Patterson Says It’s Time for New Computer Architectures and Languages

#71

Post by amckinlay »

I want a language where you can express time and constraints on time within the language and the type system. I want to be able to guarantee program correctness, pre-calculate fine-grained energy usage, optimize for energy/power-saving mode usage, interface with asynchronous signals, and whatnot -- all with respect to program execution at the ISA-level within some hard real-time constraints.

Compilers make optimizations using detailed instruction timing information, but as far as I know, these details do not bubble up to the surface in any programming language.

It may be wise to keep these details under the surface at the compiler level, but for 8-bit architectures, it would be awesome to have a language where you have explicit control of time.

Re: David Patterson Says It’s Time for New Computer Architectures and Languages

#73

Post by Avshalom »

agumonkey wrote: post #21

Probably old news, but forth cpu arrays are so radically fun .. I wonder why they're not interesting. Every forth core can pass forth to its neighbors, forth is very expressive yet tiny since it's a stack language. Anyway my 2cents

I think it's more obscure than uninteresting.

Fundamentally though it's a transputer-on-a-chip so there is an existing base of research on writing/optimizing that sort of thing.

Re: David Patterson Says It’s Time for New Computer Architectures and Languages

#75

Post by philipkglass »

philipkglass wrote: post #7

Are there languages that have first-class support for representing/optimizing memory hierarchy characteristics? Optimizing C compilers, for example, may have extensions to force specific alignments: https://software.intel.com/en-us/articles/coding-for-perform... But I'm not aware of languages where e.g. declaring alignments is part of the base language. Awareness of L1, L2, L3 cache characteristics, plus NUMA nodes,…

niftich, chubot: Thanks for the pointers to Sequoia and citations thereof. It looks very interesting. That is the sort of thing I had in mind when I asked my question. There are a lot of citations to follow up on.

the8472, RcouF1uZ4gsC, stochastic_monk: Thanks for highlighting the language-level alignment support in Rust and newer revisions of C and C++.

glangdale, regarding "I have a project half on the boil that's aiming to produce a language aimed at these kind of usages. I'm figuring that the supposed insult hurled at C ("structured assembly") isn't really an insult at all but that someone should actually do that." -- That's great! I would like to see that language.

Re: David Patterson Says It’s Time for New Computer Architectures and Languages

#76

Post by the8472 »

tabtab wrote: post #37
chubot wrote: post #32

Earlier quoted context omitted.

Yes, a pithier way of saying this is: Software is a gas; it expands to fill its container - Nathan Myhrvold Bad performance isn't really a software design problem; it's an economics problem (ditto for security). You could speed up the browser by 2x now, or reduce it's memory usage by 2x, and websites would be exactly as slow after a few months. I'm not trying to be negative here, just stating an unfortunate systems d…

I generally agree: it's about weighing trade-offs, and calling software companies "lazy" is perhaps an oversimplification. However, I do believe the speed of light and size of atoms puts an upper limit on the degree you can keep throwing hardware at the problem. We may continue to find tricks such as quantum computing, but I suspect it will get ever tougher. There's a theoretical limit to how small you squeeze data a…

> We may continue to find tricks such as quantum computing

Quantum computing does not magically speed up general purpose computing tasks. We only know a handful of algorithms where quantum computers provide algorithmic complexity reductions and even that that does not mean they necessarily calculate fast in terms of IPC, they just calculate previously intractable problems in reasonable timescales.

TL;DR: you won't pop quantum GPUs/CPUs into your computer and suddenly get 50 times the framerates in DOOM.

Re: David Patterson Says It’s Time for New Computer Architectures and Languages

#77

Post by Waterluvian »

amckinlay wrote: post #71

I want a language where you can express time and constraints on time within the language and the type system. I want to be able to guarantee program correctness, pre-calculate fine-grained energy usage, optimize for energy/power-saving mode usage, interface with asynchronous signals, and whatnot -- all with respect to program execution at the ISA-level within some hard real-time constraints. Compilers make optimizati…

Are you suggesting a language where you could hypothetically look at your IDE and it'll tell you via static analysis, "this code block takes x cpu units. On a Y core this is 0.95ns".

Never thought about that. That would be so cool.

Re: David Patterson Says It’s Time for New Computer Architectures and Languages

#78

Post by the8472 »

ArtWomb wrote: post #47

In gamedev, Nvidia's Turing enabled real time rendering at 4k 60fps could be "future-proof" well into the next decade. I'm just not sure end users are clamoring for more photo-realism. Instead, future of computing turns toward optimizing for the experience. With 3D printed form factors and smart haptics. European startup Canatu provides a glimpse of what carbon nano tube (CNT) sheets make possible: https://canatu.com…

Now it's time for display technology to catch up. Once things like light fields roll around those 4k will seem laughable.

> I'm just not sure end users are clamoring for more photo-realism.

People are definitely making fun of characters looking waxy, fire effects looking cheap, shadows being pixelated etc.

Plus this is just the first generation of realtime raytracing. It's not like the entire scenes will be raytraced, just some parts will be raytracing-assisted, e.g. lighting. The next generations will most likely enable a higher percentage of the scenes being based on tracing.

Re: David Patterson Says It’s Time for New Computer Architectures and Languages

#79

Post by munificent »

amckinlay wrote: post #71

I want a language where you can express time and constraints on time within the language and the type system. I want to be able to guarantee program correctness, pre-calculate fine-grained energy usage, optimize for energy/power-saving mode usage, interface with asynchronous signals, and whatnot -- all with respect to program execution at the ISA-level within some hard real-time constraints. Compilers make optimizati…

Part of the reason most languages obscure this is because it's a moving target.

If a language let you say, "this chunk of code here should run in 7 cycles", what happens when a new optimization finds a way to reduce that, or a new architecture comes up where that operation gets slower but lots of others get faster?

I'm not arguing against your desire, just explaining that it's not unreasonable that we're where we are now. We've gotten so used to language portability, that it's good to remember how painful it can be to lose that. It's no fun having to rewrite all your code every time a new chip comes out.

Re: David Patterson Says It’s Time for New Computer Architectures and Languages

#80

Post by baddox »

Waterluvian wrote: post #77
amckinlay wrote: post #71

I want a language where you can express time and constraints on time within the language and the type system. I want to be able to guarantee program correctness, pre-calculate fine-grained energy usage, optimize for energy/power-saving mode usage, interface with asynchronous signals, and whatnot -- all with respect to program execution at the ISA-level within some hard real-time constraints. Compilers make optimizati…

Are you suggesting a language where you could hypothetically look at your IDE and it'll tell you via static analysis, "this code block takes x cpu units. On a Y core this is 0.95ns". Never thought about that. That would be so cool.

There are lots of attributes that are provably impossible to statically determine about a computer program. Whether the program halts is the obvious example, but Rice's theorem generalizes this to effectively any attribute of a computer program you would be likely to care about.

https://en.wikipedia.org/wiki/Rice%27s_theorem

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