time performance -global or local

[econy]

MCU program, no cache, can anybody explain the performance comparison between global and local variables?

[Lost User]

Your question is far from clear; does it have anything to do with C/C++/MFC?

Veni, vidi, abiit domum

[econy]

I just not very clear which way is better in programming a C program, that will run on a 32 bit RISC Microcontroller platform. Using globals or using locals as possible as many.

[econy]

as I understand, local in stack, and possibly replaced by register. but local variable needs push/pop operation. Globals in RAM, no need to allocate memory/retrieve memory every time

[Lost User]

Given the speed of most modern processors the time difference will most likely be too small to measure.

Veni, vidi, abiit domum

[Aescleal]

It depends on the architecture and how quickly the processor can form an address in comparison to how fast an instruction gets through the pipeline. The only way you're going to know for sure is to measure the speed of your app using both types of variables.

[econy]

If a code block locates in an infinite loop, choose locals, then with locality principle, it is better than globals, I think. If a code blcck just run a few times, accessing global vs push/pop stack operation, which one is better?