pthread_attr_setinheritsched for sched_setscheduler - c++

Question

I try to test one application which will run several threads with different priority , so the following is my test ap , run in linux x86_64 :
pthread_spinlock_t orderspinlock ;
int iGlbCnt=0 ;
void * donothing(void *arg)
{
pthread_attr_t attr;
pthread_attr_init (&attr);
//int s = pthread_attr_setinheritsched (&attr, PTHREAD_INHERIT_SCHED );
int s = pthread_attr_setinheritsched (&attr, PTHREAD_EXPLICIT_SCHED );
if( s != 0 ){
printf("pthread_attr_setinheritsched error \n");
exit(0) ;
}
int ipriority = (int)(long) arg ;
const char *sched_policy[] = {
"SCHED_OTHER",
"SCHED_FIFO",
"SCHED_RR",
"SCHED_BATCH"
};
struct sched_param sp = {
.sched_priority = ipriority
};
pid_t pid = getpid();
printf("pid=(%d)\n",pid);
sched_setscheduler(pid, SCHED_RR, &sp);
printf("Scheduler Policy is %s.\n", sched_policy[sched_getscheduler(pid)]);
pthread_detach(pthread_self());
int icnt=0;
while(1){
usleep( 1 ) ;
pthread_spin_lock(&orderspinlock) ;
iGlbCnt++ ;
pthread_spin_unlock(&orderspinlock) ;
if( ++icnt > 10000000 )
break;
}
printf("thread done...(%d)\n",iGlbCnt);
}
int main(int argc, char **argv)
{
pthread_spin_init(&orderspinlock, 0);
pthread_attr_t attr;
pthread_attr_init (&attr);
//int s = pthread_attr_setinheritsched (&attr, PTHREAD_INHERIT_SCHED );
int s = pthread_attr_setinheritsched (&attr, PTHREAD_EXPLICIT_SCHED );
if( s != 0 ){
printf("pthread_attr_setinheritsched error \n");
exit(0) ;
}
pthread_t tid;
pthread_create(&tid, NULL, &donothing, (void *)(long) 80);
pthread_create(&tid, NULL, &donothing, (void *)(long) 10);
while( 1 )
sleep( 5 ) ;
}
and g++ --std=c++11 y.cpp -pthread -o y.exe
run :
sudo chrt -r -v 66 ./y.exe
another terminal watch the threads by
top -H -p `pidof y.exe`
I see the threads PR are -67 , -67 , -11 , after both donothing threads die ,
the main thread PR = -11 , What should I do so that all three threads
priority are -81 , -11 , -67 and the main thread keep in -67 to the end ?!
Edit :
int policy = 2 ;
s = pthread_setschedparam(pthread_self(),policy,&sp) ;
instead of :
pid_t pid = getpid();
sched_setscheduler(pid, SCHED_RR, &sp);
look work fine to me .