cpustates: added transition timeline option

Added an option to generate a timeline of state transitions, in
contrast to the existing timeline of computed states. This is primarily
intended for debugging of the latter, but may also be useful for certain
kinds of analyses.

wlauto/utils/power.py

@@ -340,6 +340,36 @@ def gather_core_states(system_state_stream, freq_dependent_idle_states=None):  #
         yield (system_state.timestamp, core_states)
 
 
+def record_state_transitions(reporter, stream):
+    for event in stream:
+        if event.kind == 'transition':
+            reporter.record_transition(event)
+        yield event
+
+
+class PowerStateTransitions(object):
+
+    def __init__(self, filepath ):
+        self.filepath = filepath
+        self._wfh = open(filepath, 'w')
+        self.writer = csv.writer(self._wfh)
+        headers = ['timestamp', 'cpu_id', 'frequency', 'idle_state']
+        self.writer.writerow(headers)
+
+    def update(self, timestamp, core_states):  # NOQA
+        # Just recording transitions, not doing anything
+        # with states.
+        pass
+
+    def record_transition(self, transition):
+        row = [transition.timestamp, transition.cpu_id,
+               transition.frequency, transition.idle_state]
+        self.writer.writerow(row)
+
+    def report(self):
+        self._wfh.close()
+
+
 class PowerStateTimeline(object):
 
     def __init__(self, filepath, core_names, idle_state_names):
@@ -626,7 +656,8 @@ def report_power_stats(trace_file, idle_state_names, core_names, core_clusters,
                        num_idle_states, first_cluster_state=sys.maxint,
                        first_system_state=sys.maxint, use_ratios=False,
                        timeline_csv_file=None, cpu_utilisation=None,
-                       max_freq_list=None, start_marker_handling='error'):
+                       max_freq_list=None, start_marker_handling='error',
+                       transitions_csv_file=None):
     # pylint: disable=too-many-locals,too-many-branches
     trace = TraceCmdTrace(trace_file,
                           filter_markers=False,
@@ -663,6 +694,12 @@ def report_power_stats(trace_file, idle_state_names, core_names, core_clusters,
 
     event_stream = trace.parse()
     transition_stream = stream_cpu_power_transitions(event_stream)
+    if transitions_csv_file:
+        trans_reporter = PowerStateTransitions(transitions_csv_file)
+        reporters.append(trans_reporter)
+        recorded_trans_stream = record_state_transitions(trans_reporter, transition_stream)
+        power_state_stream = ps_processor.process(recorded_trans_stream)
+    else:
         power_state_stream = ps_processor.process(transition_stream)
     core_state_stream = gather_core_states(power_state_stream)
 
@@ -700,6 +737,7 @@ def main():
         cpu_utilisation=args.cpu_utilisation,
         max_freq_list=args.max_freq_list,
         start_marker_handling=args.start_marker_handling,
+        transitions_csv_file=args.transitions_file,
     )
 
     parallel_report = reports.pop(0)
@@ -773,6 +811,11 @@ def parse_arguments():  # NOQA
                         A timeline of core power states will be written to the specified file in
                         CSV format.
                         ''')
+    parser.add_argument('-T', '--transitions-file', metavar='FILE',
+                        help='''
+                        A timeline of core power state transitions will be
+                        written to the specified file in CSV format.
+                        ''')
     parser.add_argument('-u', '--cpu-utilisation', metavar='FILE',
                         help='''
                         A timeline of cpu(s) utilisation will be written to the specified file in