Is there something about my question that suggests that I don't know what I want to ask?

Question

I've recently asked Going to try to move some of my scipy/numpy calculation to GPU, how to avoid disappointing results? I've taken some time to explain the computational problem, that it runs in numpy and might require calls to scipy.special. One of the things I would like to try to improve its speed is to move part of the calculation to a GPU and have outlined some concerns I have before going out and investing in a GPU.

In it I link to three similar questions asking for help/advice on moving a calculation to GPU

• CUDA & Python for numerical integration and solving differential equations
• Writing code on the CPU while developing, running it on the GPU when live - which approach?
• GPU vs CPU calculation

Each of these questions was relatively well received, and has received two answers with good advice.

None of these questions received a request of specific code. In each case the OP was trusted to be asking the question to which they would like an answer.

However under my question there is more than one request for specific code.

Of course there are many ways that one can try to speed up a program and especially a python script. It's important to structure the arrays properly and there are options (e.g. numba) for more efficient compilation.

But this question is not about that. Similarly to the three linked questions, this questions asks for specific pointers for how to avoid being disappointed purchasing a GPU and finding out it does not add performance. They can be expensive.

In a comment I've said:

In this case I feel the script is distracting and will tend to attract well-meaning answers about how to better script it which is not what this question is about.

I feel that the direction the comments have taken has somewhat derailed my question. Of course they are all well-meaning and are reaching out to try to help, but I also feel that unlike the authors of the three linked questions I am not being given sufficient credibility that I know the question to which I would like answers.

Is there something about the way my question is written that might be causing this?

Answer 1

Not my comments on the linked post, but I can speculate based on my impression of the differences between your post and the previous ones. I think the big difference was in the scope of the routine you were trying to speed up.

• In the first question, they are asking for a library for GPU differential equation solvers. This was the broadest problem domain of the three posts, but even still, ODE solvers are fairly well established, to point where it's very common to have "solve this ODE" as just a single line in your code. While its fairly high level, you could think of "solve this ODE" as a single operation.

• The second question was effectively asking how GPUs would affect the time for matrix multiplication. Even more so than the first example, this would qualify as trying to speed up a single operation.

• The last question was about using GPUs for computing large factorials, so essentially about splitting up the work of many multiplications. Again, a single operation.

Your question (or at least the background, more on this below) focused on being able to do numpy or special function evaluations, which are fairly general and could potentially refer to a wide variety of different operations that may or may not benefit from GPUs. A lot of users seemed to infer from this that your question was an XY problem: you had decided that you needed GPUs to speed up your program (X), when your real issue may just have been a slow algorithm for some step in the process (Y). While GPUs wouldn't necessarily be the wrong way to go, they thought they might be just papering over the real problem.

But based on this meta post, your comments, and the title of your question, the mathematical problem you are solving is not the core of your question. You are just trying to determine, in general, how to best (as in best practices/principles, rather than the optimal in terms of performance) move over code from a CPU to a GPU implementation to improve performance.

While in general I think background is great to include, I think here the particular computational problem you are solving is distracting from the question you want answered. So I would say to remove the problem specific details and just leave the latter part of your question.