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

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

#171

Post by api »

garyclarke27 wrote: post #146
api wrote: post #66

Here's something that seems shockingly under-explored to me: languages that incorporate relational data structures natively. We have SQL of course, but SQL is not a general purpose language and is (intentionally) often not Turing-complete. I'm imagining something like Go, Ruby, JavaScript, or Rust with native tables, queries, and other SQL-ish relational data structures. The long term goal would be to kill the age-ol…

Agreed - Improving SQL should be a research focus eg new options to make it more logical such as FROM clause before SELECT clause (much better for tooling) Add Immutable options (to make it truly functional), optimize for Optane persistent memory, add native GUI/ HTML support (like Foxpro) to make it much easier to wire up IO between tables and display/input. Add NOT IN Foreign Keys. PostgreSQL desperatly needs auto…

Not improved SQL! Modern languages with native relational data models. Not a DSL inside a language but something native to the language and one with its normal syntax.

The ideas within SQL are powerful but the syntax would need a dust off and would need to be integrated into a modern language.

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

#172

Post by gpderetta »

philipkglass wrote: post #100
OldHand2018 wrote: post #85

Earlier quoted context omitted.

Does anyone else have real-world Itanium experience? We've got a couple 5+ year old HP Integrity servers running OpenVMS on Itanium at work that we use to batch process large ASCII vendor files in an ETL process written in C. They certainly don't embarrass themselves. We'll be connecting them to a new Pure Storage SAN in a few months and the IT guys are really excited to see what happens to performance. I take the sa…

I used Itanium from 2003-2006 for scientific computing on a big cluster. For that purpose it was much faster than Intel's Xeons of similar vintage. It was also significantly faster than the MIPS and POWER systems we had. Caveats: - The simulation suite that I used most heavily was developed in-house at the same lab that bought the hardware. It was profiled and tuned specifically for our hardware. The development team…

Numerical code is usually the best case for VLIW machines. It is not surprising that Itanium did well there.

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

#173

Post by hawski »

pjmlp wrote: post #159
distances wrote: post #154

Earlier quoted context omitted.

In other words, Itanium only failed because there was competition.

No, Itanium failed because Intel made the error to allow other companies to compete on the x86 space with their patents cross licensing deal. Competition from other architectures was always there.

In other words, Itanium only failed because there was competition in the x86 space.

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

#174

Post by patrickg_zill »

graycat wrote: post #145
ssvss wrote: post #138

Earlier quoted context omitted.

What book would you recommend to know more about SOC?

Start with books on dynamic programming, discrete time, discrete space space, no uncertainty. There's a nice one by Dreyfus and Law, The Art and Theory of Dynamic Programming that also gets into the stochastic case. It's called dynamic programming because the program , that is, the planning, changes dynamically over time as learn more and more as time passes. D&L show a nice result that could be used for some first c…

Curious if you have evaluated any of the APL family of languages as being useful for your work.

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

#175

Post by chriswarbo »

calebh wrote: post #107
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…

It turns out that it is possible to optimally minimize the number of beta reductions in a lambda calculus program. See this excellent blog post: https://medium.com/@maiavictor/some-functions-may-have-negat...

Approaches like the Abstract Algorithm (that you link to) turn out to just shift the costs elsewhere; in particular to the "book keeping" (IIUC nodes act differently depending on which "path" we're traversing, and keeping track of that exactly cancels out the benefits of optimal sharing).

For example, see links at https://www.reddit.com/r/haskell/comments/2zqtfk/why_isnt_an...

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

#176

Post by scott_s »

marcosdumay wrote: post #52
scott_s wrote: post #35

Earlier quoted context omitted.

The most obvious failure for the Cell architecture was that it was horrendous to program. That was partly caused by the lack of memory coherence between the PPE (main core that ran the OS) and the SPEs (the faster cores meant for offloading computations to), but also caused by a lack of developer tools. The main lesson I would take away from Cell is that you want to design an architecture that allows gradual performa…

Developer tools come with time, and time is the one thing non-standard architectures completely lacked until recently. I still don't think the Cell had much future, but we will never be sure. (Also, the Cell had complete memory coherence.)

Yes, I mispoke by saying the SPEs lacked memory coherence, since you used the same physical addresses to load memory into the SPEs local storage. What I meant is that the SPEs are divorced from the normal memory hierarchy. You needed to explicitly retrieve and send all memory from each SPEs, which was a significant burden on programmers.

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

#177

Post by alexisread »

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…

So there are languages that can do these things individually:

Dedalus is an evolution of datalog, incorporating the notion of time in the type system. You're better off working with an abstract version of time, for portability reasons - the compiler can look at the timing specs to optimize resource usage, otherwise you're into VHDL territory and your only recourse is simulation of your system to reason about it, due to complexity .

Fine grained energy usage would be specific to say the SOC you're using, eg. for the CC1310 there are specific modes for low power. The compiler could potentially take care of this, but you would probably require an abstract state machine for it to optimize, eg. identify periods to go in to low power mode.

Hard realtime nearly precludes many languages due to their need for GC - there are a few realtime GCs around, but really it's better to use a language that has managed memory without GC. So after all that, you're down to a handful of suitable languages for realtime eg. Rust or Composita.

Lastly, guaranteeing program correctness is something you need to do in a high level language, to be able to capture the semantics you're tying to prove. ie. you need a language that can express higher order logic. Whether this proof step is intrinsic to the language is up to you, but you then need to map the higher-level model to your low level language. Several projects do this eg. CakeML, but the full self-verified OS doesn't exist as yet.

Interestingly there is a linguistic solution for all of this which I'm working on, just not got anything concrete to share yet - maybe in 6 months :)

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

#178

Post by uryga »

alexisread wrote: post #177
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…

So there are languages that can do these things individually: Dedalus is an evolution of datalog, incorporating the notion of time in the type system. You're better off working with an abstract version of time, for portability reasons - the compiler can look at the timing specs to optimize resource usage, otherwise you're into VHDL territory and your only recourse is simulation of your system to reason about it, due…

I'm very curious about your solution! If there's a place where I could follow the development, I'd be grateful for a link or, if it's not too much of a hassle, a ping to the email in my profile when you have something you want to show off :)

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

#179

Post by axilmar »

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,…

Wouldn't it be better if the slow RAM we have was replaced more and more by the fast RAM used in caches, before we do anything else?

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

#180

Post by alexisread »

baddox wrote: post #80
Waterluvian wrote: post #77

Earlier quoted context omitted.

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

There are many properties as such, but we can still prove many properties about a program despite non-deterministic behaviour, using hidden logic https://cseweb.ucsd.edu/~goguen/pps/hherb.ps

As such, a proof system which incorporates behavioural specification is highly desirable.

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