cpu: modified with review feedback

x86-global-inst-tracker.py:
- change the incorrect use of comment styly
- add more comments about the usage of the script and the purpose of
the script

src/cpu/probes/inst_tracker.cc:
- change the way of stopListening to use the manager function to remove
listeners. If in the future, the ProbeListner object does not call the
manager to remove itself in the destruction, then we should call it
here.
- fix stlying

src/cpu/probes/inst_tracker.hh:
- fix stlying

Change-Id: I6f3d745e15883a8a702593f72f984e0d4cc4c526

configs/example/gem5_library/x86-global-inst-tracker.py

@@ -24,6 +24,33 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+"""
+
+This script demonstrates how to use global and local instruction trackers to
+monitor and control the simulation based on the number of instructions
+committed.
+
+This script will create a global instruction tracker to manage each local
+instruction tracker and connects each local instruction tracker to a core.
+The global instruction tracker will raise an event when the number of
+instructions committed across all cores reaches a certain threshold.
+
+In this script, we expect to start monitorning the instruction committed from
+the start of the simulation and raise a SIMPOINT_BEGIN exit event when all
+cores in combination have committed 100,000,000 instructions. Then, we will
+change the threshold to 20,000 instructions and raise another SIMPOINT_BEGIN
+event when the new threshold is reached. Finally, we will stop listening to
+instructions.
+
+Usage:
+------
+
+scons build/X86/gem5.opt
+./build/X86/gem5.opt [--debug-flags=InstTracker] \
+    configs/example/gem5_library/x86-global-inst-tracker.py
+
+"""
+
 import m5
 from m5.objects import (
     GlobalInstTracker,
@@ -42,14 +69,6 @@ from gem5.resources.resource import obtain_resource
 from gem5.simulate.exit_event import ExitEvent
 from gem5.simulate.simulator import Simulator
 
-"""
-
-Usage:
-
-gem5.opt configs/example/gem5_library/x86-global-inst-tracker.py
-
-"""
-
 cache_hierarchy = PrivateL1CacheHierarchy(
     l1d_size="64kB",
     l1i_size="64kB",
@@ -118,13 +137,10 @@ def max_inst_handler():
     # we can stop listening to instructions
     for tracker in all_trackers:
         tracker.stopListening()
-    """
-    similarly, we can start listening to instructions again by calling:
-
-    for tracker in all_trackers:
-        tracker.startListening()
-
-    """
+    # similarly, we can start listening to instructions again by calling:
+    #
+    # for tracker in all_trackers:
+    #     tracker.startListening()
     m5.stats.dump()
     m5.stats.reset()
     yield False