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#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <pthread.h>
volatile pthread_t running;
volatile int thread_switches;
volatile int done = 0;
void * thread(void *x)
{
pthread_t self = pthread_self();
long long self_count = 0;
long long avg = 0;
int avg_calculations = 0;
/* let all threads start */
sleep(1);
while(1) {
if (running == self) { /* still this thread running */
self_count++;
/*
* Safety net -- when running high priority we can prevent
* main() from running and stopping the program.
*/
if (self_count > 100000000) break;
} else { /* just switched to this thread */
running = self;
thread_switches++;
if(self_count)
{
/* Re-calculate average */
avg *= avg_calculations;
avg += self_count;
avg_calculations++;
avg /= avg_calculations;
}
/*
* Another safety net
*/
if (done || (thread_switches > 300)) break;
self_count = 1;
}
}
printf("Thread %d exiting, average count between switches = %lld, self_count = %lld\n",
*(int *)x, avg, self_count);
pthread_exit((void*) 0);
}
int main(void)
{
void *status;
pthread_attr_t attr;
pthread_t t1, t2;
struct sched_param param;
int one=1;
int two=2;
/* Add your scheduler setup logic here */
pthread_attr_init(&attr);
pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
/* Use this line for the first run only */
// pthread_attr_setschedpolicy(&attr, SCHED_OTHER);
/* End of first run only code */
/* Use these lines for the second run only */
// pthread_attr_setschedpolicy(&attr, SCHED_RR);
// param.sched_priority = 10;
// pthread_attr_setschedparam(&attr, ¶m);
/* End of second run only code */
/* Use these lines for the third run only */
pthread_attr_setschedpolicy(&attr, SCHED_FIFO);
param.sched_priority = 10;
pthread_attr_setschedparam(&attr, ¶m);
/* End of third run only code */
if (pthread_create(&t1, &attr, thread, &one)) exit(1);
if (pthread_create(&t2, &attr, thread, &two)) exit(1);
sleep(10); /* let program run 10 seconds */
done = 1;
pthread_join(t1, &status);
pthread_join(t2, &status);
printf("Total thread switches: %d\n", thread_switches);
exit(0);
}
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