- Switch events to use a priority enum instead of integers.

This lets us centralize priorities so we can see what's going on.
- Shift serialize & cpu-switch events to happen before CPU ticks (to be
consistent with starting new CPU on same cycle instead of next cycle).
- Get rid of unnecessary bus stats reset callback.

cpu/simple_cpu/simple_cpu.cc:
sim/debug.cc:
sim/eventq.hh:
sim/serialize.cc:
sim/sim_events.cc:
sim/sim_events.hh:
    Switch events to use a priority enum instead of integers.
    This lets us centralize priorities so we can see what's going on.

--HG--
extra : convert_revision : 510d79b43c0a1c97a10eb65916f7335b1de8b956

5 files changed, 55 insertions, 34 deletions

diff --git a/sim/debug.cc b/sim/debug.cc
index 6f3789c96..09c604a95 100644
--- a/sim/debug.cc
+++ b/sim/debug.cc
@@ -64,10 +64,10 @@ class DebugBreakEvent : public Event
 // constructor: schedule at specified time
 //
 DebugBreakEvent::DebugBreakEvent(EventQueue *q, Tick _when)
-    : Event(q)
+    : Event(q, Debug_Break_Pri)
 {
     setFlags(AutoDelete);
-    schedule(_when, -20000);
+    schedule(_when);
 }
 
 //
diff --git a/sim/eventq.hh b/sim/eventq.hh
index dc1b2d9af..36cb402a8 100644
--- a/sim/eventq.hh
+++ b/sim/eventq.hh
@@ -97,11 +97,52 @@ class Event : public Serializable, public FastAlloc
 
   public:
 
+    /// Event priorities, to provide tie-breakers for events scheduled
+    /// at the same cycle.  Most events are scheduled at the default
+    /// priority; these values are used to control events that need to
+    /// be ordered within a cycle.
+    enum Priority {
+        /// Breakpoints should happen before anything else, so we
+        /// don't miss any action when debugging.
+        Debug_Break_Pri		= -100,
+
+        /// For some reason "delayed" inter-cluster writebacks are
+        /// scheduled before regular writebacks (which have default
+        /// priority).  Steve?
+        Delayed_Writeback_Pri	=   -1,
+
+        /// Default is zero for historical reasons.
+        Default_Pri		=    0,
+
+        /// CPU switches schedule the new CPU's tick event for the
+        /// same cycle (after unscheduling the old CPU's tick event).
+        /// The switch needs to come before any tick events to make
+        /// sure we don't tick both CPUs in the same cycle.
+        CPU_Switch_Pri		=   31,
+
+        /// Serailization needs to occur before tick events also, so
+        /// that a serialize/unserialize is identical to an on-line
+        /// CPU switch.
+        Serialize_Pri		=   32,
+
+        /// CPU ticks must come after other associated CPU events
+        /// (such as writebacks).
+        CPU_Tick_Pri		=   50,
+
+        /// Statistics events (dump, reset, etc.) come after
+        /// everything else, but before exit.
+        Stat_Event_Pri		=   90,
+
+        /// If we want to exit on this cycle, it's the very last thing
+        /// we do.
+        Sim_Exit_Pri		=  100
+    };
+
     /*
      * Event constructor
      * @param queue that the event gets scheduled on
      */
-    Event(EventQueue *q, int p = 0)
+    Event(EventQueue *q, Priority p = Default_Pri)
         : queue(q), next(NULL), _priority(p), _flags(None),
 #if TRACING_ON
           when_created(curTick), when_scheduled(0),
@@ -122,15 +163,9 @@ class Event : public Serializable, public FastAlloc
     /// Schedule the event with the current priority or default priority
     void schedule(Tick t);
 
-    /// Schedule the event with a specific priority
-    void schedule(Tick t, int priority);
-
     /// Reschedule the event with the current priority
     void reschedule(Tick t);
 
-    /// Reschedule the event with a specific priority
-    void reschedule(Tick t, int priority);
-
     /// Remove the event from the current schedule
     void deschedule();
 
@@ -284,13 +319,6 @@ Event::schedule(Tick t)
 }
 
 inline void
-Event::schedule(Tick t, int p)
-{
-    _priority = p;
-    schedule(t);
-}
-
-inline void
 Event::deschedule()
 {
     assert(scheduled());
@@ -314,13 +342,6 @@ Event::reschedule(Tick t)
 }
 
 inline void
-Event::reschedule(Tick t, int p)
-{
-    _priority = p;
-    reschedule(t);
-}
-
-inline void
 EventQueue::schedule(Event *event)
 {
     insert(event);
diff --git a/sim/serialize.cc b/sim/serialize.cc
index 82d295384..95aacc361 100644
--- a/sim/serialize.cc
+++ b/sim/serialize.cc
@@ -259,7 +259,7 @@ class SerializeEvent : public Event
 };
 
 SerializeEvent::SerializeEvent(Tick _when, Tick _repeat)
-    : Event(&mainEventQueue, 990), repeat(_repeat)
+    : Event(&mainEventQueue, Serialize_Pri), repeat(_repeat)
 {
     setFlags(AutoDelete);
     schedule(_when);
diff --git a/sim/sim_events.cc b/sim/sim_events.cc
index 7456e788b..a31da18dd 100644
--- a/sim/sim_events.cc
+++ b/sim/sim_events.cc
@@ -68,14 +68,14 @@ SimExitEvent::description()
 //
 CountedExitEvent::CountedExitEvent(EventQueue *q, const std::string &_cause,
                                    Tick _when, int &_downCounter)
-    : Event(q),
+    : Event(q, Sim_Exit_Pri),
       cause(_cause),
       downCounter(_downCounter)
 {
     // catch stupid mistakes
     assert(downCounter > 0);
 
-    schedule(_when, 1000);
+    schedule(_when);
 }
 
 
diff --git a/sim/sim_events.hh b/sim/sim_events.hh
index c4db248e0..4a8e7c115 100644
--- a/sim/sim_events.hh
+++ b/sim/sim_events.hh
@@ -43,23 +43,23 @@ class SimExitEvent : public Event
 
   public:
     SimExitEvent(const std::string &_cause, int c = 0)
-        : Event(&mainEventQueue), cause(_cause),
+        : Event(&mainEventQueue, Sim_Exit_Pri), cause(_cause),
           code(c)
-        { schedule(curTick, 1000); }
+        { schedule(curTick); }
 
     SimExitEvent(Tick _when, const std::string &_cause, int c = 0)
-        : Event(&mainEventQueue), cause(_cause),
+        : Event(&mainEventQueue, Sim_Exit_Pri), cause(_cause),
           code(c)
-        { schedule(_when, 1000); }
+        { schedule(_when); }
 
     SimExitEvent(EventQueue *q, const std::string &_cause, int c = 0)
-        : Event(q), cause(_cause), code(c)
-        { schedule(curTick, 1000); }
+        : Event(q, Sim_Exit_Pri), cause(_cause), code(c)
+        { schedule(curTick); }
 
     SimExitEvent(EventQueue *q, Tick _when, const std::string &_cause,
                  int c = 0)
-        : Event(q), cause(_cause), code(c)
-        { schedule(_when, 1000); }
+        : Event(q, Sim_Exit_Pri), cause(_cause), code(c)
+        { schedule(_when); }
 
     void process();	// process event