Standard Switch: Drain the system before switching CPUs

When switching from an atomic CPU to any of the timing CPUs, a drain is
unnecessary since no events are scheduled in atomic mode. However, when
trying to switch CPUs starting with a timing CPU, there may be events
scheduled. This change ensures that all events are drained from the system
by calling m5.drain before switching CPUs.

configs/common/Simulation.py

@@ -453,6 +453,7 @@ def run(options, root, testsys, cpu_class):
         # manually.  You DON'T need to resume after just switching
         # CPUs if you haven't changed anything on the system level.
 
+        m5.doDrain(testsys)
         m5.changeToTiming(testsys)
         m5.switchCpus(switch_cpu_list)
         m5.resume(testsys)
@@ -469,7 +470,7 @@ def run(options, root, testsys, cpu_class):
             print "Switching CPUS @ tick %s" % (m5.curTick())
             print "Simulation ends instruction count:%d" % \
                     (testsys.switch_cpus_1[0].max_insts_any_thread)
-            m5.drain(testsys)
+            m5.doDrain(testsys)
             m5.switchCpus(switch_cpu_list1)
             m5.resume(testsys)
 

src/python/m5/simulate.py

@@ -203,7 +203,6 @@ def changeToTiming(system):
               (type(system), objects.Root, objects.System)
 
     if system.getMemoryMode() != objects.params.timing:
-        doDrain(system)
         print "Changing memory mode to timing"
         for obj in system.descendants():
             obj.changeTiming(objects.params.timing)