CH5: Multiprocessor and real time scheduling

Author: dalmia

5-Process Scheduling/a.out

@@ -0,0 +1,46 @@
+#include <pthread.h>
+#include <stdio.h>
+
+#define NUM_THREADS 5
+
+void *runner(void *param);
+
+int main(int argc, char *argv[])
+{
+ int i, scope;
+ pthread_t tid[NUM_THREADS];
+ pthread_attr_t attr;
+
+ /* get the default attributes */
+ pthread_attr_init(&attr);
+
+ /* first inquire on the current scope */
+ if(pthread_attr_getscope(&attr, &scope) != 0){
+ fprintf(stderr, "Unable to get scheduling scope\n");
+ }else{
+ if(scope == PTHREAD_SCOPE_PROCESS) printf("PTHREAD_SCOPE_PROCESS\n");
+ else if(scope == PTHREAD_SCOPE_SYSTEM) printf("PTHREAD_SCOPE_SYSTEM\n");
+ else fprintf(stderr, "Illegal scope value\n");
+ }
+
+ /* set the scheduling algorithm to PCS or SCS */
+ pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM);
+
+ /* create the threads */
+ for(i = 0;i < NUM_THREADS; i++){
+ pthread_create(&tid[i], &attr, runner, NULL);
+ }
+
+ /* now join on each thread */
+ for(i = 0; i < NUM_THREADS; i++){
+ pthread_join(tid[i], NULL);
+ }
+}
+
+/* Each thread will begin control in this function */
+void *runner(void *param)
+{
+ printf("Inside runner\n");
+
+ pthread_exit(0);
+}

5-Process Scheduling/pthread_scheduling.c

@@ -0,0 +1,43 @@
+#include <pthread.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#define NUM_THREADS 5
+
+void *runner(void *param);
+
+int main(){
+ int i, policy;
+ pthread_t tid[NUM_THREADS];
+ pthread_attr_t attr;
+
+ pthread_attr_init(&attr);
+
+ if(pthread_attr_getschedpolicy(&attr, &policy) != 0){
+ fprintf(stderr, "Unable to get policy\n");
+ }else{
+ if(policy == SCHED_OTHER) printf("SCHED_OTHER\n");
+ else if(policy == SCHED_RR) printf("SCHED_RR\n");
+ else if(policy == SCHED_FIFO) printf("SCHED_FIFO\n");
+ }
+
+ if(pthread_attr_setschedpolicy(&attr, SCHED_FIFO) != 0){
+ fprintf(stderr, "Error setting policy\n");
+ }
+
+ for(i = 0; i < NUM_THREADS; i++){
+ pthread_create(&tid[i], &attr, runner, NULL);
+ }
+
+ for(i = 0; i < NUM_THREADS; i++){
+ pthread_join(tid[i], NULL);
+ }
+}
+
+void *runner(void *param){
+ printf("Inside runner\n");
+ sleep(3);
+ printf("Exiting runner\n");
+
+ pthread_exit(0);
+}