[SOLVED] CS /* Checks that when the alarm clock wakes up threads, the

/* Checks that when the alarm clock wakes up threads, the
higher-priority threads run first. */

#include
#include tests/threads/tests.h
#include threads/init.h
#include threads/malloc.h
#include threads/semaphore.h
#include threads/thread.h
#include devices/timer.h

static thread_func alarm_priority_thread;
static int64_t wake_time;
static struct semaphore wait_sema;

void
test_alarm_priority(void)
{
int i;

/* This test does not work with the MLFQS. */
ASSERT(!thread_mlfqs);

wake_time = timer_ticks() + 5 * TIMER_FREQ;
semaphore_init(&wait_sema, 0);

for (i = 0; i < 10; i++) {int priority = PRI_DEFAULT – (i + 5) % 10 – 1;char name[16];snprintf(name, sizeof name, “priority %d”, priority);thread_create(name, priority, alarm_priority_thread, NULL);}thread_set_priority(PRI_MIN);for (i = 0; i < 10; i++)semaphore_down(&wait_sema);}static voidalarm_priority_thread(void *aux UNUSED){/* Busy-wait until the current time changes. */int64_t start_time = timer_ticks();while (timer_elapsed(start_time) == 0)continue;/* Now we know we’re at the very beginning of a timer tick, so we can call timer_sleep() without worrying about races between checking the time and a timer interrupt. */timer_sleep(wake_time – timer_ticks());/* Print a message on wake-up. */msg(“Thread %s woke up.”, thread_name());semaphore_up(&wait_sema);}