Why would it need to? Application-level software shouldn't need to care about that, it's way too low-level. If I do: #include <stdio.h> int main(void

Why would it need to? Application-level software shouldn't need to care about that, it's way too low-level. If I do: #include <stdio.h> int main(void) { printf("Hello from some core!\n"); return 0; } that code doesn't need to think about which core it runs on, or even if there are multiple cores. Of course it does nothing to support multiple cores, but it does need some core to run on. The OS just schedules the process onto some core, and then it can of course monitor the process' performance and decide to move it, if it detects a better fit. All of that is invisible to the process itself. Of course high-performance/server software might want to actually care and use OS-specific API:s and services to deal with that, but those are the exception.