Linux Scheduler (not using all cores on multi-core machine) RHEL6
- by User512
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
