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, 10 insertions, 1 deletions

diff --git a/src/sim/Root.py b/src/sim/Root.py
index 44f768c0b..c6f7cfba6 100644
--- a/src/sim/Root.py
+++ b/src/sim/Root.py
@@ -1,5 +1,6 @@
 # Copyright (c) 2005-2007 The Regents of The University of Michigan
-# Copyright (c) 2010 Advanced Micro Devices, Inc.
+# Copyright (c) 2010-2013 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
@@ -60,6 +61,14 @@ class Root(SimObject):
     type = 'Root'
     cxx_header = "sim/root.hh"
 
+    # By default, root sim object and hence all other sim objects schedule
+    # event on the eventq with index 0.
+    eventq_index = 0
+
+    # Simulation Quantum for multiple main event queue simulation.
+    # Needs to be set explicitly for a multi-eventq simulation.
+    sim_quantum = Param.Tick(0, "simulation quantum")
+
     full_system = Param.Bool("if this is a full system simulation")
 
     # Time syncing prevents the simulation from running faster than real time.