I'm seeing strange behavior on one of my servers (running RHEL 6). There seems to be something wrong with the scheduler. Here's the test program I'm using: #include <stdio.h> #include <unistd.h> #include <stdlib.h> void RunClient(int i) { printf("Starting client %d\n", i); while (true) { } } int main(int argc, char** argv) { for (int i = 0; i < 4; ++i) { pid_t p_id = fork(); if (p_id == -1) { perror("fork"); } else if (p_id == 0) { RunClient(i); exit(0); } } return 0; } This machine has a lot more than 4 cores so we'd expect all processes to be running at 100%. When I check on top, the cpu usage varies. Sometimes it's split (100%, 33%, 33%, 33%), other times it's split (100%, 100%, 50%, 50%). When I try this test on another server of ours (running RHEL 5), there are no issues (it's 100%, 100%, 100%, 100%) as expected. What's causing this and how can I fix it? Thanks