Change MaxMemorySize to MaxMemoryPages

[bkchr]

We should set the max memory for the executor in pages (64KiB) and not in bytes. The wasm memory is always a multiple of a page and we should use the same terminology.

Sorry to not have brought up this earlier 🙈 I just realized while doing some other things 🙈

[s0me0ne-unkn0wn]

I don't have a strong opinion if it's beneficial or not. Substrate executor deals with paging issues itself where needed, and external Wastime interfaces often use bytes to represent different types of limits (e.g. StoreLimitsBuilder::memory_size() and memory_guaranteed_dense_image_size()).

I mean, ExecutorParams are intended to expose executor semantics to the chain. If we want to operate pages, why not change executor semantics itself then (along with changing it here)? That would also somewhat simplify code on the Substrate executor side.

@koute any thoughts from you?

[koute]

LGTM

Even if some of wasmtime's interfaces take a number of bytes instead of a number of pages (for convenience's sake I suppose) it doesn't change the fact that WASM memory can only grow in page increments, so it makes sense to define the limit also in page increments.

[s0me0ne-unkn0wn]

I'd anyway consider changing that on the Substrate executor side for the sake of consistency, otherwise looks good.

[bkchr]

I'd anyway consider changing that on the Substrate executor side for the sake of consistency, otherwise looks good.

The change is already coming here: #6730 This is the reason I have opened this pr :D