Question

Is this loop busy waiting, I would think the wait call takes care of that. If it is, how can it be fixed to not busy wait?

id = fork();
for (i = 0; i < 20; i++)
{
    switch (id)
    {
             case 0:
                /* do stuff with child */
                exit(0);
             default:
             {
                 if (children>=3) {
                     int s;
                     wait(&s);
                     children--;
                 }
                 children++;
                 id = fork();
             }
    }
}

Answer 1

wait will cause the kernel to select other jobs that are not marked as blocked, so this isn’t a case of busy-waiting. Also isn’t switch a bit excessive for a fork(), why not use a simple if statement?