ruby: consumer: avoid using receiver side clock

A set of patches was recently committed to allow multiple clock domains
in ruby. In those patches, I had inadvertently made an incorrect use of
the clocks. Suppose object A needs to schedule an event on object B. It
was possible that A accesses B's clock to schedule the event. This is not
possible in actual system. Hence, changes are being to the Consumer class
so as to avoid such happenings. Note that in a multi eventq simulation,
this can possibly lead to an incorrect simulation.

There are two functions in the Consumer class that are used for scheduling
events. The first function takes in the relative delay over the current time
as the argument and adds the current time to it for scheduling the event.
The second function takes in the absolute time (in ticks) for scheduling the
event. The first function is now being moved to protected section of the
class so that only objects of the derived classes can use it. All other
objects will have to specify absolute time while scheduling an event
for some consumer.

2 files changed, 5 insertions, 7 deletions

diff --git a/src/mem/ruby/common/Consumer.cc b/src/mem/ruby/common/Consumer.cc
index b7d31ccb0..9f3735709 100644
--- a/src/mem/ruby/common/Consumer.cc
+++ b/src/mem/ruby/common/Consumer.cc
@@ -31,19 +31,15 @@
 void
 Consumer::scheduleEvent(Cycles timeDelta)
 {
-    timeDelta += em->curCycle();
-    scheduleEventAbsolute(timeDelta);
+    scheduleEventAbsolute(em->clockEdge(timeDelta));
 }
 
 void
-Consumer::scheduleEventAbsolute(Cycles timeAbs)
+Consumer::scheduleEventAbsolute(Tick evt_time)
 {
-    Tick evt_time = em->clockPeriod() * timeAbs;
     if (!alreadyScheduled(evt_time)) {
         // This wakeup is not redundant
         ConsumerEvent *evt = new ConsumerEvent(this);
-        assert(timeAbs > em->curCycle());
-
         em->schedule(evt, evt_time);
         insertScheduledWakeupTime(evt_time);
     }
diff --git a/src/mem/ruby/common/Consumer.hh b/src/mem/ruby/common/Consumer.hh
index c1b4d70b1..57ee69f3e 100644
--- a/src/mem/ruby/common/Consumer.hh
+++ b/src/mem/ruby/common/Consumer.hh
@@ -87,8 +87,10 @@ class Consumer
         m_scheduled_wakeups.erase(time);
     }
 
+    void scheduleEventAbsolute(Tick timeAbs);
+
+  protected:
     void scheduleEvent(Cycles timeDelta);
-    void scheduleEventAbsolute(Cycles timeAbs);
 
   private:
     Tick m_last_scheduled_wakeup;