tests/kernel/sched/schedule_api: Restore spinning for timer alignment

tests/kernel/sched/schedule_api/src/main.c

@@ -10,6 +10,28 @@
 K_THREAD_STACK_DEFINE(tstack, STACK_SIZE);
 K_THREAD_STACK_ARRAY_DEFINE(tstacks, MAX_NUM_THREAD, STACK_SIZE);
 
+void spin_for_ms(int ms)
+{
+#if defined(CONFIG_X86_64) && defined(CONFIG_QEMU_TARGET)
+	/* qemu-system-x86_64 has a known bug with the hpet device
+	 * where it will drop interrupts if you try to spin on the
+	 * counter.
+	 */
+	k_busy_wait(ms * 1000);
+#else
+	u32_t t32 = k_uptime_get_32();
+
+	while (k_uptime_get_32() - t32 < ms) {
+		/* In the posix arch, a busy loop takes no time, so
+		 * let's make it take some
+		 */
+		if (IS_ENABLED(CONFIG_ARCH_POSIX)) {
+			k_busy_wait(50);
+		}
+	}
+#endif
+}
+
 /**
  * @brief Test scheduling
  *

tests/kernel/sched/schedule_api/src/test_sched.h

@@ -23,6 +23,8 @@ struct thread_data {
 	int executed;
 };
 
+void spin_for_ms(int ticks);
+
 void test_priority_cooperative(void);
 void test_priority_preemptible(void);
 void test_yield_cooperative(void);

tests/kernel/sched/schedule_api/src/test_sched_timeslice_reset.c

@@ -51,7 +51,7 @@ static void thread_tslice(void *p1, void *p2, void *p3)
 	/* Keep the current thread busy for more than one slice, even though,
 	 * when timeslice used up the next thread should be scheduled in.
 	 */
-	k_busy_wait(1000 * BUSY_MS);
+	spin_for_ms(BUSY_MS);
 	k_sem_give(&sema);
 }
 

tests/kernel/sched/schedule_api/src/test_slice_scheduling.c

@@ -55,7 +55,7 @@ static void thread_tslice(void *p1, void *p2, void *p3)
 		 * even though, when timeslice used up the next thread
 		 * should be scheduled in.
 		 */
-		k_busy_wait(1000 * BUSY_MS);
+		spin_for_ms(BUSY_MS);
 		k_sem_give(&sema1);
 	}
 
@@ -102,7 +102,7 @@ void test_slice_scheduling(void)
 		 * even though, when timeslice used up the next thread
 		 * should be scheduled in.
 		 */
-		k_busy_wait(1000 * BUSY_MS);
+		spin_for_ms(BUSY_MS);
 
 		/* relinquish CPU and wait for each thread to complete*/
 		for (int i = 0; i < NUM_THREAD; i++) {