OCaml Bigarray: slower than builtin arrays?

Question

What are the downsides of using Bigarray when interfacing with C is not an issue? Are they slower, in particular for small 2D matrices?

Answer 1

Just based on looking through the implementations, I'd say that bigarrays might be slower if you create large numbers of short-lived arrays. It looks like the memory for them is managed outside the usual OCaml GC, which handles short-lived objects extremely well.

You also might find that accesses to bigarrays aren't inlined, whereas accesses to the built-in arrays would be.

On the other hand, built-in arrays are going to have an extra indirection for two-dimensions.

If the performance really matters, you'll probably have to benchmark your particular application.

Answer 2

The main downside is right there in the type - bigarrays can hold only small subset of primitive types