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

To find out the number of processors instead of using /proc/cpuinfo just run:

nproc

To run a process on a group of specific processors:

taskset --cpu-list 1,2 my_command 

will say that my command can only run on cpu 1 or 2.

To run a program on 4 processors doing 4 different things use parameterization. The argument to the program tells it to do something different:

for i in `seq 0 1 3`;
do 
  taskset --cpu-list $i my_command $i;
done

A good example of this is dealing with 8 million operation in an array so that 0 to (2mil-1) goes to processor 1, 2mil to (4mil-1) to processor 2 and so on.

You can look at the load on each process by installing htop using apt-get/yum and running at the command line:

 htop