scripts/analyse-locks-simpletrace.py: script to analyse lock times

This script allows analysis of mutex acquisition and hold times based
on a trace file. Given a trace control file of:

  qemu_mutex_lock
  qemu_mutex_locked
  qemu_mutex_unlock

And running with:

  $QEMU $QEMU_ARGS -trace events=./lock-trace

You can analyse the results with:

  ./scripts/analyse-locks-simpletrace.py trace-events-all ./trace-21812
Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

scripts/analyse-locks-simpletrace.py

+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#
+# Analyse lock events and compute statistics
+#
+# Author: Alex Bennée <alex.bennee@linaro.org>
+#
+
+import os
+import simpletrace
+import argparse
+import numpy as np
+
+class MutexAnalyser(simpletrace.Analyzer):
+    "A simpletrace Analyser for checking locks."
+
+    def __init__(self):
+        self.locks = 0
+        self.locked = 0
+        self.unlocks = 0
+        self.mutex_records = {}
+
+    def _get_mutex(self, mutex):
+        if not mutex in self.mutex_records:
+            self.mutex_records[mutex] = {"locks": 0,
+                                         "lock_time": 0,
+                                         "acquire_times": [],
+                                         "locked": 0,
+                                         "locked_time": 0,
+                                         "held_times": [],
+                                         "unlocked": 0}
+
+        return self.mutex_records[mutex]
+
+    def qemu_mutex_lock(self, timestamp, mutex, filename, line):
+        self.locks += 1
+        rec = self._get_mutex(mutex)
+        rec["locks"] += 1
+        rec["lock_time"] = timestamp[0]
+        rec["lock_loc"] = (filename, line)
+
+    def qemu_mutex_locked(self, timestamp, mutex, filename, line):
+        self.locked += 1
+        rec = self._get_mutex(mutex)
+        rec["locked"] += 1
+        rec["locked_time"] = timestamp[0]
+        acquire_time = rec["locked_time"] - rec["lock_time"]
+        rec["locked_loc"] = (filename, line)
+        rec["acquire_times"].append(acquire_time)
+
+    def qemu_mutex_unlock(self, timestamp, mutex, filename, line):
+        self.unlocks += 1
+        rec = self._get_mutex(mutex)
+        rec["unlocked"] += 1
+        held_time = timestamp[0] - rec["locked_time"]
+        rec["held_times"].append(held_time)
+        rec["unlock_loc"] = (filename, line)
+
+
+def get_args():
+    "Grab options"
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--output", "-o", type=str, help="Render plot to file")
+    parser.add_argument("events", type=str, help='trace file read from')
+    parser.add_argument("tracefile", type=str, help='trace file read from')
+    return parser.parse_args()
+
+if __name__ == '__main__':
+    args = get_args()
+
+    # Gather data from the trace
+    analyser = MutexAnalyser()
+    simpletrace.process(args.events, args.tracefile, analyser)
+
+    print ("Total locks: %d, locked: %d, unlocked: %d" %
+           (analyser.locks, analyser.locked, analyser.unlocks))
+
+    # Now dump the individual lock stats
+    for key, val in sorted(analyser.mutex_records.iteritems(),
+                           key=lambda (k,v): v["locks"]):
+        print ("Lock: %#x locks: %d, locked: %d, unlocked: %d" %
+               (key, val["locks"], val["locked"], val["unlocked"]))
+
+        acquire_times = np.array(val["acquire_times"])
+        if len(acquire_times) > 0:
+            print ("  Acquire Time: min:%d median:%d avg:%.2f max:%d" %
+                   (acquire_times.min(), np.median(acquire_times),
+                    acquire_times.mean(), acquire_times.max()))
+
+        held_times = np.array(val["held_times"])
+        if len(held_times) > 0:
+            print ("  Held Time: min:%d median:%d avg:%.2f max:%d" %
+                   (held_times.min(), np.median(held_times),
+                    held_times.mean(), held_times.max()))
+
+        # Check if any locks still held
+        if val["locks"] > val["locked"]:
+            print ("  LOCK HELD (%s:%s)" % (val["locked_loc"]))
+            print ("  BLOCKED   (%s:%s)" % (val["lock_loc"]))