system call sched_yield() doesn't work on Linux 2.2

[Mohit Aron]

Hi,
        the system call sched_yield() doesn't seem to work on Linux 2.2. Does
anyone know of a kernel patch that fixes this ? 

Attached below is a small program that uses pthreads and demonstrates that
sched_yield() doesn't work. Basically, the program creates two threads that
alternatively try to yield CPU to each other.


- Mohit


#include <stdio.h>
#include <sched.h>
#include <pthread.h>

static pthread_t thread1, thread2;


static void *thread1_func(void *arg)
{
  int i;

  for (i=0; i < 5 ;i++) {
    printf("Thread1\n");
    if (sched_yield()) printf("error in yielding\n");
  }
}

static void *thread2_func(void *arg)
{
  int i;

  for (i=0; i < 5 ;i++) {
    printf("Thread2\n");
    if (sched_yield()) printf("error in yielding\n");
  }
}


int main(int argc, char **argv)
{
  pthread_create(&thread1, NULL, thread1_func, NULL);
  pthread_create(&thread2, NULL, thread2_func, NULL);

  sleep(10);

  return 0;
}