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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)

#63

Post by ziedaniel1 »

Very cool idea - but unless I'm missing something, this seems very slow.

I just wrote a simple loop in C++ to sum up 0 to 2^30. With a single thread without any optimizations it runs in 1.7s on my laptop -- matching Bend's performance on an RTX 4090! With -O3 it vectorizes the loop to run in less than 80ms.

    #include 

    int main() {
      int sum = 0;
      for (int i = 0; i

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

#65

Post by rroriz »

ziedaniel1 wrote: post #63

Very cool idea - but unless I'm missing something, this seems very slow. I just wrote a simple loop in C++ to sum up 0 to 2^30. With a single thread without any optimizations it runs in 1.7s on my laptop -- matching Bend's performance on an RTX 4090! With -O3 it vectorizes the loop to run in less than 80ms. #include int main() { int sum = 0; for (int i = 0; i

I think the point is that Bend in a much higher level than C++. But to be fair: I also may be missing the point!

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

#66

Post by Twirrim »

For what it's worth, I ported the sum example to pure python.

    def sum(depth, x):
        if depth == 0:
          return x
        else:
          fst = sum(depth-1, x*2+0) # adds the fst half
          snd = sum(depth-1, x*2+1) # adds the snd half
          return fst + snd
        
    print(sum(30, 0))
under pypy3 it executes in 0m4.478s, single threaded. Under python 3.12, it executed in 1m42.148s, again single threaded. I mention that because you include benchmark information:

    CPU, Apple M3 Max, 1 thread: 3.5 minutes
    CPU, Apple M3 Max, 16 threads: 10.26 seconds
    GPU, NVIDIA RTX 4090, 32k threads: 1.88 seconds
The bend single-threaded version has been running for 42 minutes on my laptop, is consuming 6GB of memory, and still hasn't finished (12th Gen Intel(R) Core(TM) i7-1270P, Ubuntu 24.04). That seems to be an incredibly slow interpreter. Has this been tested or developed on anything other than Macs / aarch64?

I appreciate this is early days, but it's hard to get excited about what seems to be incredibly slow performance from a really simple example you give. If the simple stuff is slow, what does that mean for the complicated stuff?

If I get a chance tonight, I'll re-run it with `-s` argument, see if I get anything helpful.

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

#68

Post by 5- »

rroriz wrote: post #65
ziedaniel1 wrote: post #63

Very cool idea - but unless I'm missing something, this seems very slow. I just wrote a simple loop in C++ to sum up 0 to 2^30. With a single thread without any optimizations it runs in 1.7s on my laptop -- matching Bend's performance on an RTX 4090! With -O3 it vectorizes the loop to run in less than 80ms. #include int main() { int sum = 0; for (int i = 0; i

I think the point is that Bend in a much higher level than C++. But to be fair: I also may be missing the point!

here is the same loop finishing in one second on my laptop, single-threaded, in a very high-level language, q:

  q)\t sum til floor 2 xexp 30
  1031

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

#70

Post by klabb3 »

This is very exciting. I don’t have any GPU background, but I have been worrying a lot about CUDA cementating itself in the ecosystem. Here devs don’t need CUDA directly which would help decoupling the ecosystem from cynical mega corps, always good! Anyway enough politics..

Tried to see what the language is like beyond hello world and found the guide[1]. It looks like a Python and quacks like a Haskell? For instance, variables are immutable, and tree-like divide and conquer data structures/algorithms are promoted for getting good results. That makes sense I guess! I’m not surprised to see a functional core, but I’m surprised to see the pythonic frontend, not that it matters much. I must say I highly doubt that it will make it much easier for Python devs to learn Bend though, although I don’t know if that’s the goal.

What are some challenges in programming with these kind of restrictions in practice? Also, is there good FFI options?

[1]: https://github.com/HigherOrderCO/bend/blob/main/GUIDE.md

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