Is stack memory contiguous physically in Linux?

Question

As far as I can see, stack memory is contiguous in virtual memory address, but stack memory is also contiguous physically? And does this have something to do with the stack

Answer 1

It is a complex topic.

Heap and stack have (usually) the same memory and memory type (MTRR, cache setting per page, etc.). [mmap, files, drivers could have different strategies, or when user explicit change it].

Stack could be faster, because it is often used. When you call a function, parameters and local variables are put into stack, so the cache is fresh. Additionally, because functions call and return often, probably there is some more stack in the other cache level, and seldom the top of stack is paged (because it was used recently).

So cache could be faster, but just if you have few variables. If you allow large arrays on stack e.g. with alloca, the advantage disappear.

In general, this is a very complex topic, and it is better not to optimize too much, because it could cause complex code, so more difficult to refactor and high level optimization of code. (e.g. on multi-dimentional arrays, the order of indices (and so memory) and loops could improve sensible the speed, but also quickly the code will be impossible to maintain).