1 files changed, 31 insertions, 0 deletions

diff --git a/pintos-progos/tests/threads/priority-change.c b/pintos-progos/tests/threads/priority-change.c
new file mode 100644
index 0000000..810b05a
--- /dev/null
+++ b/pintos-progos/tests/threads/priority-change.c
@@ -0,0 +1,31 @@
+/* Verifies that lowering a thread's priority so that it is no
+   longer the highest-priority thread in the system causes it to
+   yield immediately. */
+
+#include <stdio.h>
+#include "tests/threads/tests.h"
+#include "threads/init.h"
+#include "threads/thread.h"
+
+static thread_func changing_thread;
+
+void
+test_priority_change (void) 
+{
+  /* This test does not work with the MLFQS. */
+  ASSERT (!thread_mlfqs);
+
+  msg ("Creating a high-priority thread 2.");
+  thread_create ("thread 2", PRI_DEFAULT + 1, changing_thread, NULL);
+  msg ("Thread 2 should have just lowered its priority.");
+  thread_set_priority (PRI_DEFAULT - 2);
+  msg ("Thread 2 should have just exited.");
+}
+
+static void
+changing_thread (void *aux UNUSED) 
+{
+  msg ("Thread 2 now lowering priority.");
+  thread_set_priority (PRI_DEFAULT - 1);
+  msg ("Thread 2 exiting.");
+}