diff --git a/adb/device.py b/adb/device.py
index 57f17fc..b6eaad6 100644
--- a/adb/device.py
+++ b/adb/device.py
@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+import logging
 import os
 import re
 import subprocess
@@ -146,10 +147,12 @@
         return result, out
 
     def _simple_call(self, cmd):
+        logging.info(' '.join(self.adb_cmd + cmd))
         return subprocess.check_output(
             self.adb_cmd + cmd, stderr=subprocess.STDOUT)
 
     def shell(self, cmd):
+        logging.info(' '.join(self.adb_cmd + ['shell'] + cmd))
         cmd = self._make_shell_cmd(cmd)
         out = subprocess.check_output(cmd)
         rc, out = self._parse_shell_output(out)
@@ -161,6 +164,7 @@
 
     def shell_nocheck(self, cmd):
         cmd = self._make_shell_cmd(cmd)
+        logging.info(' '.join(cmd))
         p = subprocess.Popen(
             cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
         out, _ = p.communicate()
@@ -190,6 +194,9 @@
     def usb(self):
         return self._simple_call(['usb'])
 
+    def reboot(self):
+        return self._simple_call(['reboot'])
+
     def root(self):
         return self._simple_call(['root'])
 
diff --git a/init/perfboot.py b/init/perfboot.py
new file mode 100755
index 0000000..2cd4699
--- /dev/null
+++ b/init/perfboot.py
@@ -0,0 +1,411 @@
+#!/usr/bin/env python
+# Copyright (C) 2015 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Record the event logs during boot and output them to a file.
+
+This script repeats the record of each event log during Android boot specified
+times. By default, interval between measurements is adjusted in such a way that
+CPUs are cooled down sufficiently to avoid boot time slowdown caused by CPU
+thermal throttling. The result is output in a tab-separated value format.
+
+Examples:
+
+Repeat measurements 10 times. Interval between iterations is adjusted based on
+CPU temperature of the device.
+
+$ ./perfboot.py --iterations=10
+
+Repeat measurements 20 times. 60 seconds interval is taken between each
+iteration.
+
+$ ./perfboot.py --iterations=20 --interval=60
+
+Repeat measurements 20 times, show verbose output, output the result to
+data.tsv, and read event tags from eventtags.txt.
+
+$ ./perfboot.py --iterations=30 -v --output=data.tsv --tags=eventtags.txt
+"""
+
+import argparse
+import atexit
+import cStringIO
+import inspect
+import logging
+import math
+import os
+import re
+import subprocess
+import sys
+import threading
+import time
+
+sys.path.append(os.path.dirname(os.path.dirname(__file__)))
+import adb
+
+# The default event tags to record.
+_DEFAULT_EVENT_TAGS = [
+    'boot_progress_start',
+    'boot_progress_preload_start',
+    'boot_progress_preload_end',
+    'boot_progress_system_run',
+    'boot_progress_pms_start',
+    'boot_progress_pms_system_scan_start',
+    'boot_progress_pms_data_scan_start',
+    'boot_progress_pms_scan_end',
+    'boot_progress_pms_ready',
+    'boot_progress_ams_ready',
+    'boot_progress_enable_screen',
+]
+
+
+class IntervalAdjuster(object):
+    """A helper class to take suffficient interval between iterations."""
+
+    # CPU temperature values per product used to decide interval
+    _CPU_COOL_DOWN_THRESHOLDS = {
+        'flo': 40,
+        'flounder': 40000,
+        'razor': 40,
+        'volantis': 40000,
+    }
+    # The interval between CPU temperature checks
+    _CPU_COOL_DOWN_WAIT_INTERVAL = 10
+    # The wait time used when the value of _CPU_COOL_DOWN_THRESHOLDS for
+    # the product is not defined.
+    _CPU_COOL_DOWN_WAIT_TIME_DEFAULT = 120
+
+    def __init__(self, interval, device):
+        self._interval = interval
+        self._device = device
+        self._temp_paths = device.shell(
+            ['ls', '/sys/class/thermal/thermal_zone*/temp']).splitlines()
+        self._product = device.get_prop('ro.build.product')
+        self._waited = False
+
+    def wait(self):
+        """Waits certain amount of time for CPUs cool-down."""
+        if self._interval is None:
+            self._wait_cpu_cool_down(self._product, self._temp_paths)
+        else:
+            if self._waited:
+                print 'Waiting for %d seconds' % self._interval
+                time.sleep(self._interval)
+        self._waited = True
+
+    def _get_cpu_temp(self, threshold):
+        max_temp = 0
+        for temp_path in self._temp_paths:
+            temp = int(self._device.shell(['cat', temp_path]).rstrip())
+            max_temp = max(max_temp, temp)
+            if temp >= threshold:
+                return temp
+        return max_temp
+
+    def _wait_cpu_cool_down(self, product, temp_paths):
+        threshold = IntervalAdjuster._CPU_COOL_DOWN_THRESHOLDS.get(
+            self._product)
+        if threshold is None:
+            print 'No CPU temperature threshold is set for ' + self._product
+            print ('Just wait %d seconds' %
+                   IntervalAdjuster._CPU_COOL_DOWN_WAIT_TIME_DEFAULT)
+            time.sleep(IntervalAdjuster._CPU_COOL_DOWN_WAIT_TIME_DEFAULT)
+            return
+        while True:
+            temp = self._get_cpu_temp(threshold)
+            if temp < threshold:
+                logging.info('Current CPU temperature %s' % temp)
+                return
+            print 'Waiting until CPU temperature (%d) falls below %d' % (
+                temp, threshold)
+            time.sleep(IntervalAdjuster._CPU_COOL_DOWN_WAIT_INTERVAL)
+
+
+class WatchdogTimer(object):
+    """A timer that makes is_timedout() return true in |timeout| seconds."""
+    def __init__(self, timeout):
+        self._timedout = False
+
+        def notify_timeout():
+            self._timedout = True
+        self._timer = threading.Timer(timeout, notify_timeout)
+        self._timer.start()
+
+    def is_timedout(self):
+        return self._timedout
+
+    def cancel(self):
+        self._timer.cancel()
+
+
+def readlines_unbuffered(proc):
+    """Read lines from |proc|'s standard out without buffering."""
+    while True:
+        buf = []
+        c = proc.stdout.read(1)
+        if c == '' and proc.poll() is not None:
+            break
+        while c != '\n':
+            if c == '' and proc.poll() is not None:
+                break
+            buf.append(c)
+            c = proc.stdout.read(1)
+        yield ''.join(buf)
+
+
+def disable_dropbox(device):
+    """Removes the files created by Dropbox and avoids creating the files."""
+    device.root()
+    device.wait()
+    device.shell(['rm', '-rf', '/system/data/dropbox'])
+    original_dropbox_max_files = device.shell(
+        ['settings', 'get', 'global', 'dropbox_max_files']).rstrip()
+    device.shell(['settings', 'put', 'global', 'dropbox_max_files', '0'])
+    return original_dropbox_max_files
+
+
+def restore_dropbox(device, original_dropbox_max_files):
+    """Restores the dropbox_max_files setting."""
+    device.root()
+    device.wait()
+    if original_dropbox_max_files == 'null':
+        device.shell(['settings', 'delete', 'global', 'dropbox_max_files'])
+    else:
+        device.shell(['settings', 'put', 'global', 'dropbox_max_files',
+                      original_dropbox_max_files])
+
+
+def init_perf(device, output, record_list, tags):
+    device.wait()
+    build_type = device.get_prop('ro.build.type')
+    original_dropbox_max_files = None
+    if build_type != 'user':
+        # Workaround for Dropbox issue (http://b/20890386).
+        original_dropbox_max_files = disable_dropbox(device)
+
+    def cleanup():
+        try:
+            if record_list:
+                print_summary(record_list, tags[-1])
+                output_results(output, record_list, tags)
+            if original_dropbox_max_files is not None:
+                restore_dropbox(device, original_dropbox_max_files)
+        except subprocess.CalledProcessError, RuntimeError:
+            pass
+    atexit.register(cleanup)
+
+
+def read_event_tags(tags_file):
+    """Reads event tags from |tags_file|."""
+    if not tags_file:
+        return _DEFAULT_EVENT_TAGS
+    tags = []
+    with open(tags_file) as f:
+        for line in f:
+            if '#' in line:
+                line = line[:line.find('#')]
+            line = line.strip()
+            if line:
+                tags.append(line)
+    return tags
+
+
+def make_event_tags_re(tags):
+    """Makes a regular expression object that matches event logs of |tags|."""
+    return re.compile(r'(?P<pid>[0-9]+) +[0-9]+ I (?P<tag>%s): (?P<time>\d+)' %
+                      '|'.join(tags))
+
+
+def get_values(record, tag):
+    """Gets values that matches |tag| from |record|."""
+    keys = [key for key in record.keys() if key[0] == tag]
+    return [record[k] for k in sorted(keys)]
+
+
+def get_last_value(record, tag):
+    """Gets the last value that matches |tag| from |record|."""
+    values = get_values(record, tag)
+    if not values:
+        return 0
+    return values[-1]
+
+
+def output_results(filename, record_list, tags):
+    """Outputs |record_list| into |filename| in a TSV format."""
+    # First, count the number of the values of each tag.
+    # This is for dealing with events that occur multiple times.
+    # For instance, boot_progress_preload_start and boot_progress_preload_end
+    # are recorded twice on 64-bit system. One is for 64-bit zygote process
+    # and the other is for 32-bit zygote process.
+    values_counter = {}
+    for record in record_list:
+        for tag in tags:
+            # Some record might lack values for some tags due to unanticipated
+            # problems (e.g. timeout), so take the maximum count among all the
+            # record.
+            values_counter[tag] = max(values_counter.get(tag, 1),
+                                      len(get_values(record, tag)))
+
+    # Then creates labels for the data. If there are multiple values for one
+    # tag, labels for these values are numbered except the first one as
+    # follows:
+    #
+    # event_tag event_tag2 event_tag3
+    #
+    # The corresponding values are sorted in an ascending order of PID.
+    labels = []
+    for tag in tags:
+        for i in range(1, values_counter[tag] + 1):
+            labels.append('%s%s' % (tag, '' if i == 1 else str(i)))
+
+    # Finally write the data into the file.
+    with open(filename, 'w') as f:
+        f.write('\t'.join(labels) + '\n')
+        for record in record_list:
+            line = cStringIO.StringIO()
+            invalid_line = False
+            for i, tag in enumerate(tags):
+                if i != 0:
+                    line.write('\t')
+                values = get_values(record, tag)
+                if len(values) < values_counter[tag]:
+                    invalid_line = True
+                    # Fill invalid record with 0
+                    values += [0] * (values_counter[tag] - len(values))
+                line.write('\t'.join(str(t) for t in values))
+            if invalid_line:
+                logging.error('Invalid record found: ' + line.getvalue())
+            line.write('\n')
+            f.write(line.getvalue())
+    print 'Wrote: ' + filename
+
+
+def median(data):
+    """Calculates the median value from |data|."""
+    data = sorted(data)
+    n = len(data)
+    if n % 2 == 1:
+        return data[n / 2]
+    else:
+        n2 = n / 2
+        return (data[n2 - 1] + data[n2]) / 2.0
+
+
+def mean(data):
+    """Calculates the mean value from |data|."""
+    return float(sum(data)) / len(data)
+
+
+def stddev(data):
+    """Calculates the standard deviation value from |value|."""
+    m = mean(data)
+    return math.sqrt(sum((x - m) ** 2 for x in data) / len(data))
+
+
+def print_summary(record_list, end_tag):
+    """Prints the summary of |record_list|."""
+    # Filter out invalid data.
+    end_times = [get_last_value(record, end_tag) for record in record_list
+                 if get_last_value(record, end_tag) != 0]
+    print 'mean: ', mean(end_times)
+    print 'median:', median(end_times)
+    print 'standard deviation:', stddev(end_times)
+
+
+def do_iteration(device, interval_adjuster, event_tags_re, end_tag):
+    """Measures the boot time once."""
+    device.wait()
+    interval_adjuster.wait()
+    device.reboot()
+    print 'Rebooted the device'
+    record = {}
+    booted = False
+    while not booted:
+        device.wait()
+        # Stop the iteration if it does not finish within 120 seconds.
+        timeout = 120
+        t = WatchdogTimer(timeout)
+        p = subprocess.Popen(
+                ['adb', 'logcat', '-b', 'events', '-v', 'threadtime'],
+                stdout=subprocess.PIPE)
+        for line in readlines_unbuffered(p):
+            if t.is_timedout():
+                print '*** Timed out ***'
+                return record
+            m = event_tags_re.search(line)
+            if not m:
+                continue
+            tag = m.group('tag')
+            event_time = int(m.group('time'))
+            pid = m.group('pid')
+            record[(tag, pid)] = event_time
+            print 'Event log recorded: %s (%s) - %d ms' % (
+                tag, pid, event_time)
+            if tag == end_tag:
+                booted = True
+                t.cancel()
+                break
+    return record
+
+
+def parse_args():
+    """Parses the command line arguments."""
+    parser = argparse.ArgumentParser(
+        description=inspect.getdoc(sys.modules[__name__]),
+        formatter_class=argparse.RawDescriptionHelpFormatter)
+    parser.add_argument('--iterations', type=int, default=5,
+                        help='Number of times to repeat boot measurements.')
+    parser.add_argument('--interval', type=int,
+                        help=('Duration between iterations. If this is not '
+                              'set explicitly, durations are determined '
+                              'adaptively based on CPUs temperature.'))
+    parser.add_argument('-o', '--output', help='File name of output data.')
+    parser.add_argument('-v', '--verbose', action='store_true',
+                        help='Show verbose output.')
+    parser.add_argument('-s', '--serial', default=os.getenv('ANDROID_SERIAL'),
+                        help='Adb device serial number.')
+    parser.add_argument('-t', '--tags', help='Specify the filename from which '
+                        'event tags are read. Every line contains one event '
+                        'tag and the last event tag is used to detect that '
+                        'the device has finished booting.')
+    return parser.parse_args()
+
+
+def main():
+    args = parse_args()
+    if args.verbose:
+        logging.getLogger().setLevel(logging.INFO)
+
+    device = adb.get_device(args.serial)
+
+    if not args.output:
+        device.wait()
+        args.output = 'perf-%s-%s.tsv' % (
+            device.get_prop('ro.build.flavor'),
+            device.get_prop('ro.build.version.incremental'))
+
+    record_list = []
+    event_tags = read_event_tags(args.tags)
+    init_perf(device, args.output, record_list, event_tags)
+    interval_adjuster = IntervalAdjuster(args.interval, device)
+    event_tags_re = make_event_tags_re(event_tags)
+    end_tag = event_tags[-1]
+    for i in range(args.iterations):
+        print 'Run #%d ' % i
+        record = do_iteration(
+            device, interval_adjuster, event_tags_re, end_tag)
+        record_list.append(record)
+
+
+if __name__ == '__main__':
+    main()