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

Post by ziedaniel1 » Fri, May 17, 2024, 7:04 PM UTC

nneonneo wrote: post #86

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

You might want to double check with objdump if the loop is actually vectorized, or if the compiler just optimizes it out. Your loop actually performs signed integer overflow, which is UB in C++; the compiler could legally output anything. If you want to avoid the UB, declare sum as unsigned (unsigned integer overflow is well-defined); the optimization will still happen but at least you’ll be guaranteed that it’ll be…

Post by vrmiguel » Fri, May 17, 2024, 7:07 PM UTC

LightMachine wrote: post #91

vrmiguel wrote: post #85

Earlier quoted context omitted.

> it is allocating 2 IC nodes for each numeric operation, while Python is not While that's true, Python would be using big integers (PyLongObject) for most of the computations, meaning every number gets allocated on the heap. If we use a Python implementation that would avoid this, like PyPy or Cython, the results change significantly: % cat sum.py def sum(depth, x): if depth == 0: return x else: fst = sum(depth-1, x…

The only claim I made is that it scales linearly with cores. Nothing else! I'm personally putting a LOT of effort to make our claims as accurate and truthful as possible, in every single place. Documentation, website, demos. I spent hours in meetings to make sure everything is correct. Yet, sometimes it feels that no matter how much effort I put, people will just find ways to misinterpret it. We published the real be…

Post by CorrectingYou » Fri, May 17, 2024, 7:08 PM UTC

Post by LightMachine » Fri, May 17, 2024, 7:16 PM UTC

IshKebab wrote: post #102

LightMachine wrote: post #91

Earlier quoted context omitted.

The only claim I made is that it scales linearly with cores. Nothing else! I'm personally putting a LOT of effort to make our claims as accurate and truthful as possible, in every single place. Documentation, website, demos. I spent hours in meetings to make sure everything is correct. Yet, sometimes it feels that no matter how much effort I put, people will just find ways to misinterpret it. We published the real be…

I think the issue is that there is the implicit claim that this is faster than some alternative. Otherwise what's the point? If you add some disclaimer like "Note: Bend is currently focused on correctness and scaling. On an absolute scale it may still be slower than single threaded Python. We plan to improve the absolute performance soon." then you won't see these comments. Also this defensive tone does not come off…

Post by LightMachine » Fri, May 17, 2024, 7:24 PM UTC

vrmiguel wrote: post #113

LightMachine wrote: post #91

Earlier quoted context omitted.

The only claim I made is that it scales linearly with cores. Nothing else! I'm personally putting a LOT of effort to make our claims as accurate and truthful as possible, in every single place. Documentation, website, demos. I spent hours in meetings to make sure everything is correct. Yet, sometimes it feels that no matter how much effort I put, people will just find ways to misinterpret it. We published the real be…

That's true, you never mentioned Python or alternatives in your README, I guess I got Mandela'ed from the comments in Hacker News, so my bad on that. People are naturally going to compare the timings and function you cite to what's available to the community right now, though, that's the only way we can picture its performance in real-life tasks. > Mojo or other languages, specifically because it generates hate Mojo…