How to control which core a process runs on?

Question

I can understand how one can write a program that uses multiple processes or threads: fork() a new process and use IPC, or create multiple threads and use those sorts of com

Answer 1

As others have mentioned, processor affinity is Operating System specific. If you want to do this outside the confines of the operating system, you're in for a lot of fun, and by that I mean pain.

That said, others have mentioned SetProcessAffinityMask for Win32. Nobody has mentioned the Linux kernel way to set processor affinity, and so I shall. You need to use the sched_setaffinity(2) system call. Here's a nice tutorial on how.

The command-line wrapper for this system call is taskset(1). e.g.
taskset -c 2,3 perf stat awk 'BEGIN{for(i=0;i<100000000;i++){}}' restricts that perf-stat of a busy-loop to running on either of core 2 or 3 (still allowing it to migrate between cores, but only between those two).