sim: simulate with multiple threads and event queues

This patch adds support for simulating with multiple threads, each of
which operates on an event queue.  Each sim object specifies which eventq
is would like to be on.  A custom barrier implementation is being added
using which eventqs synchronize.

The patch was tested in two different configurations:
1. ruby_network_test.py: in this simulation L1 cache controllers receive
   requests from the cpu. The requests are replied to immediately without
   any communication taking place with any other level.
2. twosys-tsunami-simple-atomic: this configuration simulates a client-server
   system which are connected by an ethernet link.

We still lack the ability to communicate using message buffers or ports. But
other things like simulation start and end, synchronizing after every quantum
are working.

Committed by: Nilay Vaish

1 files changed, 16 insertions, 9 deletions

diff --git a/src/sim/stat_control.cc b/src/sim/stat_control.cc
index 7a8d48ae2..83089f399 100644
--- a/src/sim/stat_control.cc
+++ b/src/sim/stat_control.cc
@@ -12,6 +12,8 @@
  * modified or unmodified, in source code or in binary form.
  *
  * Copyright (c) 2004-2005 The Regents of The University of Michigan
+ * Copyright (c) 2013 Advanced Micro Devices, Inc.
+ * Copyright (c) 2013 Mark D. Hill and David A. Wood
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -53,7 +55,7 @@
 #include "base/statistics.hh"
 #include "base/time.hh"
 #include "cpu/base.hh"
-#include "sim/eventq_impl.hh"
+#include "sim/global_event.hh"
 #include "sim/stat_control.hh"
 
 using namespace std;
@@ -68,7 +70,7 @@ namespace Stats {
 Time statTime(true);
 Tick startTick;
 
-Event *dumpEvent;
+GlobalEvent *dumpEvent;
 
 struct SimTicksReset : public Callback
 {
@@ -210,7 +212,7 @@ initSimStats()
 /**
  * Event to dump and/or reset the statistics.
  */
-class StatEvent : public Event
+class StatEvent : public GlobalEvent
 {
   private:
     bool dump;
@@ -218,8 +220,8 @@ class StatEvent : public Event
     Tick repeat;
 
   public:
-    StatEvent(bool _dump, bool _reset, Tick _repeat)
-        : Event(Stat_Event_Pri, AutoDelete),
+    StatEvent(Tick _when, bool _dump, bool _reset, Tick _repeat)
+        : GlobalEvent(_when, Stat_Event_Pri, 0),
           dump(_dump), reset(_reset), repeat(_repeat)
     {
     }
@@ -237,13 +239,18 @@ class StatEvent : public Event
             Stats::schedStatEvent(dump, reset, curTick() + repeat, repeat);
         }
     }
+
+    const char *description() const { return "GlobalStatEvent"; }
 };
 
 void
 schedStatEvent(bool dump, bool reset, Tick when, Tick repeat)
 {
-    dumpEvent = new StatEvent(dump, reset, repeat);
-    mainEventQueue.schedule(dumpEvent, when);
+    // simQuantum is being added to the time when the stats would be
+    // dumped so as to ensure that this event happens only after the next
+    // sync amongst the event queues.  Asingle event queue simulation
+    // should remain unaffected.
+    dumpEvent = new StatEvent(when + simQuantum, dump, reset, repeat);
 }
 
 void
@@ -258,7 +265,7 @@ periodicStatDump(Tick period)
      */
     if (dumpEvent != NULL && (period == 0 || dumpEvent->scheduled())) {
         // Event should AutoDelete, so we do not need to free it.
-        mainEventQueue.deschedule(dumpEvent);
+        dumpEvent->deschedule();
     }
 
     /*
@@ -288,7 +295,7 @@ updateEvents()
         (dumpEvent->scheduled() && dumpEvent->when() < curTick())) {
         // shift by curTick() and reschedule
         Tick _when = dumpEvent->when();
-        mainEventQueue.reschedule(dumpEvent, _when + curTick());
+        dumpEvent->reschedule(_when + curTick());
     }
 }