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Comment by AllegedAlec | Hacker News Reader

ctrl-f Erlang

Nothing yet? Damn...

Erlang operates on a higher level, with much, much larger chunks. Any sensible modern system will, for instance, have some sort of execution context (thread/green thread/continuation/task/whatever) associated with a single incoming HTTP request. That's very nice, and not going anywhere.

However Erlang has very little to say about parallelization of loops, or in the levels between a single loop and a HTTP request.

Nor would it be a good base for such things; if you're worried about getting maximum parallel performance out of your CPUs you pretty much by necessity need to start from a base where single-threaded performance is already roughly optimal, such as with C, C++, or Rust. Go at the very outside, and that's already a bit of a stretch in my opinion. BEAM does not have that level of single-threaded performance. There's no point in making what BEAM does fully utilize 8 CPUs in this sort of parallel performance when all that does is get you back to where a single thread of Rust can run.

(I think this is an underappreciated aspect of trying to speed things up with multiple CPUs. There's no point straining to get 8 CPUs running in some sort of complicated perfect synchronization in your slow-ish language when you could just write the same thing in a compiled language and get it on one CPU. I particularly look at the people who think that GIL removal in Python is a big deal for performance and wonder what they're thinking... a 32-core machine parallelizing Python code perfectly, with no overhead, might still be outperformed by a single-core Go process and would almost certainly be beated by a single-core Rust process. And perfect parallelization across 32 cores is a pipe dream. Unless you've already maxed out single-core performance, you don't need complicated parallelization, you need to write in a faster language to start with.)

Yeah, i too was looking for Erlang.

The thing i would really like to see is some research on how to run the Erlang concurrency model on a GPU.

There's no need for research. The answer is simple: You can't run Erlang concurrency on a GPU. GPUs fundamentally get their advantage by running the same operations on a huge set of cores across different data. They aren't just Platonically faster than CPUs, they're faster than CPUs on very, very specific tasks. Out of the context of those tasks, they are in fact massively, massively slower.

Some of the operations Erlang does, GPUs don't even want to do at all, including basic things like pattern matching. GPUs do not want that sort of code at all.

"Erlang" is being over specific here. No conventional CPU language makes sense on a GPU at all.

Not what i meant (these are superficialities).

Erlang is a concurrency-oriented language though its concurrency architecture (multicore/node/cluster/etc.) is different from that modeled by GPUs (Vectorized/SIMD/SIMT/etc.) Since share-nothing Processes (so-called Actor model) are at the heart of the Erlang Run Time System(ERTS)/BEAM it is easy to imagine a "group of Erlang processes" being mapped directly to a "group of threads in a warp on a GPU". Of course the Erlang scheduler being different (it is reduction based and not time sliced) one would need to rethink some fundamental design decisions but that should not be too out-of-the-way since the system as a whole is built for concurrency support. The other problem would be memory transfers between CPU and GPU (while still preserving immutability) but this is a more general one.

You can call out to CUDA/OpenCL/etc. from Erlang through its C interface (Kevin Smith did a presentation years ago) but i have seen no new research since then. However, there has been some new things in Elixir land notably "Nx" (Numerical Elixir) and "GPotion" (a DSL for GPU programming in Elixir).

But note that none of the above is aimed at modifying the Erlang language/runtime concurrency model itself to map to GPU models which is what i would very much like to see.

The biggest issue I think is utilizing massive GPU memory bandwidth, you really need SIMD or your GPU is just going to generate a lot of heat to do only a bit of work.

But SIMD has got nothing to do with language per se. In Erlang everything is in a module and hence i can imagine annotating a module with SIMD/SIMT attribute which would then be the hint for the ERTS to map all the processes in that module to a warp on a GPU using SIMD vectorization as needed. Of course my Erlang processes must be written to take advantage of the above and thus cannot be a general-purpose (i.e. MIMD) process.

Something like vine lang or something built on interaction nets might be close to what you are looking for. It can run on GPU.

Right; but since Erlang is already concurrency-oriented i was thinking it might be easier to add the GPU model to its runtime. See my other comment here - https://news.ycombinator.com/edit?id=45843523

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