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Bend: a high-level language that runs on GPUs (via HVM2)

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Re: Bend: a high-level language that runs on GPUs (via HVM2)

#241

Earlier quoted context omitted.

That's a great feedback actually, thank you. We'll add the disclaimer before the install instructions instead!

Relatedly, the homepage itself doesnt make it obvious it’s still alpha, or not ready, or not actually going to speed up your code this moment - claims like “automatically achieves near-ideal speedup, up to 1000+ threads” - the point is that it parallelizes code, but the word speedup makes it sound like my code will get 1000x faster. I think you can avoid this kind of criticism by setting expectations better - just pl…

It is not in alpha, nor not ready. You can use it in production today, if you want to. It is just not fast. That is different. CPython is still 100x slower than C, and is widely deployed in practice.

Re: Bend: a high-level language that runs on GPUs (via HVM2)

#243

The website claims "automatically achieves near-ideal speedup" 12x for 16x threads 51x for 16.000x threads Can someone point me to a website where it explains that this is the "ideal speedup"? Is there a formula?

Bend is intriguing --

1. Some potentially useful perspectives:

* Weak scaling vs strong scaling: https://www.kth.se/blogs/pdc/2018/11/scalability-strong-and-... ?

* ... Strong scaling, especially comparing to a modern sequential baseline, seems to be where folks are noting the author still has some work to do wrt getting to ideal speedups for what performance people care about

* There are parallel models of computation like PRAM for describing asymptomatically idealized speedups of trickier aspects of parallel code like heap usage . Bend currently seems to do a lot of stack allocations that someone writing in most parallel systems wouldn't, and the asymptomatic slowdowns would show up in these models, eg, asymptotically many unnecessary heap/stack data movements. There are a lot of these models, which are useful for being precise when making ideal speedups claims. NUMA, network topology, etc. ("Assume everyone is a sphere and...")

2. The comparisons I'd really like to see are:

* cudf, heavy.ai: how does it compare to high-level python dataframe and SQL that already run in GPUs? How is perf, and what programs do you want people to be able to write and they cannot?

* Halide and other more general purpose languages that compile to GPUs that seem closer to where Bend is going

FWIW, it's totally fine to compare to other languages.

Instead of showing it is beating everywhere, or saying ideal speedups and no comparisons, show where it is strong vs weak compared to others and diff tasks, especially progression across different releases (bend1 vs 2 vs ...), and let folks decide. There is some subset of tasks you already care about, so separate those out and show the quality you get in them, so people know what it looks like when you care + happy path. The rest becomes 'if you need these others, stay clear for now, check in again later as we know and are tracking.' Being clear that wall clock time can be slow and performance per watt can be wasteful is OK, you are looking for early adopters, not OpenAI core engineers.

Re: Bend: a high-level language that runs on GPUs (via HVM2)

#244

Earlier quoted context omitted.

The only claim I made is that it scales linearly with cores. Nothing else! The other link on the front page says: "Welcome to the Parallel Future of Computation"

Scaling with cores is synonym of parallel.

Do you think calling your project parallel is what people have an issue with or do you think it's that you're calling your project the future of parallel computation when it doesn't perform anywhere close to what already exists?

Re: Bend: a high-level language that runs on GPUs (via HVM2)

#245

OP comes around with some of the coolest things posted in HN recently, and all he gets is extensive criticism, when it is clear that this is an early version :/

It has 905 upvotes, it has received a fair share of positivity as well. Even criticism is often positive, since it expresses interest and engagement with the ideas and approach.

Re: Bend: a high-level language that runs on GPUs (via HVM2)

#246

Earlier quoted context omitted.

I would be pretty appreciated if people criticize my project. That is how you grow. If people tend hide cruel truth behind applause, the world would just crumbled.

My observation is that most criticism is useless, because people don't understand why you did things the way you did them. If you explain why, they either still don't understand, or don't agree. If the first iPhone had been presented on HN/Reddit/Twitter, everyone would criticize the lack of physical keyboard.

OP is claiming amazing results, people are poking obvious holes that good single core implementations completely rip the scalability claims to shreds. Near linear scalability is not impressive if—even at the highest throughput—the computation pales by comparison to Rust on a single core.

I do not see how the comparison to the iPhone here stands.

Re: Bend: a high-level language that runs on GPUs (via HVM2)

#250

Congratulations on the launch and hard work so far! We need projects like this. Great readme and demo as well. Every time I try to write shaders, or even peek through my fingers at CUDA C(++) code, I recoil in disbelief that we don't have high level programming yet on the GPU. I can't wait until we do. The more great projects attacking it the better in my book.

Have you looked at Futhark?
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