diff --git a/tests/base.py b/tests/base.py
index 405caa0..585f2d2 100755
--- a/tests/base.py
+++ b/tests/base.py
@@ -876,11 +876,13 @@
         self.test_root = os.path.join(tmp_root, "zuul-test")
         self.upstream_root = os.path.join(self.test_root, "upstream")
         self.git_root = os.path.join(self.test_root, "git")
+        self.state_root = os.path.join(self.test_root, "lib")
 
         if os.path.exists(self.test_root):
             shutil.rmtree(self.test_root)
         os.makedirs(self.test_root)
         os.makedirs(self.upstream_root)
+        os.makedirs(self.state_root)
 
         # Make per test copy of Configuration.
         self.setup_config()
@@ -888,6 +890,7 @@
                         os.path.join(FIXTURE_DIR,
                                      self.config.get('zuul', 'layout_config')))
         self.config.set('merger', 'git_dir', self.git_root)
+        self.config.set('zuul', 'state_dir', self.state_root)
 
         # For each project in config:
         self.init_repo("org/project")
diff --git a/tests/test_model.py b/tests/test_model.py
index 2711618..ac19383 100644
--- a/tests/test_model.py
+++ b/tests/test_model.py
@@ -12,6 +12,11 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import os
+import random
+
+import fixtures
+
 from zuul import change_matcher as cm
 from zuul import model
 
@@ -62,3 +67,76 @@
         metajob = model.Job('^job')
         job.copy(metajob)
         self._assert_job_booleans_are_not_none(job)
+
+
+class TestJobTimeData(BaseTestCase):
+    def setUp(self):
+        super(TestJobTimeData, self).setUp()
+        self.tmp_root = self.useFixture(fixtures.TempDir(
+            rootdir=os.environ.get("ZUUL_TEST_ROOT"))
+        ).path
+
+    def test_empty_timedata(self):
+        path = os.path.join(self.tmp_root, 'job-name')
+        self.assertFalse(os.path.exists(path))
+        self.assertFalse(os.path.exists(path + '.tmp'))
+        td = model.JobTimeData(path)
+        self.assertEqual(td.success_times, [0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
+        self.assertEqual(td.failure_times, [0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
+        self.assertEqual(td.results, [0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
+
+    def test_save_reload(self):
+        path = os.path.join(self.tmp_root, 'job-name')
+        self.assertFalse(os.path.exists(path))
+        self.assertFalse(os.path.exists(path + '.tmp'))
+        td = model.JobTimeData(path)
+        self.assertEqual(td.success_times, [0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
+        self.assertEqual(td.failure_times, [0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
+        self.assertEqual(td.results, [0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
+        success_times = []
+        failure_times = []
+        results = []
+        for x in range(10):
+            success_times.append(int(random.random() * 1000))
+            failure_times.append(int(random.random() * 1000))
+            results.append(0)
+            results.append(1)
+        random.shuffle(results)
+        s = f = 0
+        for result in results:
+            if result:
+                td.add(failure_times[f], 'FAILURE')
+                f += 1
+            else:
+                td.add(success_times[s], 'SUCCESS')
+                s += 1
+        self.assertEqual(td.success_times, success_times)
+        self.assertEqual(td.failure_times, failure_times)
+        self.assertEqual(td.results, results[10:])
+        td.save()
+        self.assertTrue(os.path.exists(path))
+        self.assertFalse(os.path.exists(path + '.tmp'))
+        td = model.JobTimeData(path)
+        td.load()
+        self.assertEqual(td.success_times, success_times)
+        self.assertEqual(td.failure_times, failure_times)
+        self.assertEqual(td.results, results[10:])
+
+
+class TestTimeDataBase(BaseTestCase):
+    def setUp(self):
+        super(TestTimeDataBase, self).setUp()
+        self.tmp_root = self.useFixture(fixtures.TempDir(
+            rootdir=os.environ.get("ZUUL_TEST_ROOT"))
+        ).path
+        self.db = model.TimeDataBase(self.tmp_root)
+
+    def test_timedatabase(self):
+        self.assertEqual(self.db.getEstimatedTime('job-name'), 0)
+        self.db.update('job-name', 50, 'SUCCESS')
+        self.assertEqual(self.db.getEstimatedTime('job-name'), 50)
+        self.db.update('job-name', 100, 'SUCCESS')
+        self.assertEqual(self.db.getEstimatedTime('job-name'), 75)
+        for x in range(10):
+            self.db.update('job-name', 100, 'SUCCESS')
+        self.assertEqual(self.db.getEstimatedTime('job-name'), 100)
diff --git a/tests/test_scheduler.py b/tests/test_scheduler.py
index fe7c7cc..15d33c8 100755
--- a/tests/test_scheduler.py
+++ b/tests/test_scheduler.py
@@ -34,7 +34,6 @@
 import zuul.reporter.smtp
 
 from tests.base import (
-    BaseTestCase,
     ZuulTestCase,
     repack_repo,
 )
@@ -44,40 +43,6 @@
                     '%(levelname)-8s %(message)s')
 
 
-class TestSchedulerConfigParsing(BaseTestCase):
-
-    def test_parse_skip_if(self):
-        job_yaml = """
-jobs:
-  - name: job_name
-    skip-if:
-      - project: ^project_name$
-        branch: ^stable/icehouse$
-        all-files-match-any:
-          - ^filename$
-      - project: ^project2_name$
-        all-files-match-any:
-          - ^filename2$
-    """.strip()
-        data = yaml.load(job_yaml)
-        config_job = data.get('jobs')[0]
-        sched = zuul.scheduler.Scheduler({})
-        cm = zuul.change_matcher
-        expected = cm.MatchAny([
-            cm.MatchAll([
-                cm.ProjectMatcher('^project_name$'),
-                cm.BranchMatcher('^stable/icehouse$'),
-                cm.MatchAllFiles([cm.FileMatcher('^filename$')]),
-            ]),
-            cm.MatchAll([
-                cm.ProjectMatcher('^project2_name$'),
-                cm.MatchAllFiles([cm.FileMatcher('^filename2$')]),
-            ]),
-        ])
-        matcher = sched._parseSkipIf(config_job)
-        self.assertEqual(expected, matcher)
-
-
 class TestScheduler(ZuulTestCase):
 
     def test_jobs_launched(self):
@@ -495,6 +460,46 @@
         self.assertEqual(B.reported, 2)
         self.assertEqual(C.reported, 2)
 
+    def _test_time_database(self, iteration):
+        self.worker.hold_jobs_in_build = True
+        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
+        A.addApproval('CRVW', 2)
+        self.fake_gerrit.addEvent(A.addApproval('APRV', 1))
+        self.waitUntilSettled()
+        time.sleep(2)
+
+        data = json.loads(self.sched.formatStatusJSON())
+        found_job = None
+        for pipeline in data['pipelines']:
+            if pipeline['name'] != 'gate':
+                continue
+            for queue in pipeline['change_queues']:
+                for head in queue['heads']:
+                    for item in head:
+                        for job in item['jobs']:
+                            if job['name'] == 'project-merge':
+                                found_job = job
+                                break
+
+        self.assertIsNotNone(found_job)
+        if iteration == 1:
+            self.assertIsNotNone(found_job['estimated_time'])
+            self.assertIsNone(found_job['remaining_time'])
+        else:
+            self.assertIsNotNone(found_job['estimated_time'])
+            self.assertTrue(found_job['estimated_time'] >= 2)
+            self.assertIsNotNone(found_job['remaining_time'])
+
+        self.worker.hold_jobs_in_build = False
+        self.worker.release()
+        self.waitUntilSettled()
+
+    def test_time_database(self):
+        "Test the time database"
+
+        self._test_time_database(1)
+        self._test_time_database(2)
+
     def test_two_failed_changes_at_head(self):
         "Test that changes are reparented correctly if 2 fail at head"
 
@@ -600,6 +605,36 @@
         self.assertEqual(B.reported, 2)
         self.assertEqual(C.reported, 2)
 
+    def test_parse_skip_if(self):
+        job_yaml = """
+jobs:
+  - name: job_name
+    skip-if:
+      - project: ^project_name$
+        branch: ^stable/icehouse$
+        all-files-match-any:
+          - ^filename$
+      - project: ^project2_name$
+        all-files-match-any:
+          - ^filename2$
+    """.strip()
+        data = yaml.load(job_yaml)
+        config_job = data.get('jobs')[0]
+        cm = zuul.change_matcher
+        expected = cm.MatchAny([
+            cm.MatchAll([
+                cm.ProjectMatcher('^project_name$'),
+                cm.BranchMatcher('^stable/icehouse$'),
+                cm.MatchAllFiles([cm.FileMatcher('^filename$')]),
+            ]),
+            cm.MatchAll([
+                cm.ProjectMatcher('^project2_name$'),
+                cm.MatchAllFiles([cm.FileMatcher('^filename2$')]),
+            ]),
+        ])
+        matcher = self.sched._parseSkipIf(config_job)
+        self.assertEqual(expected, matcher)
+
     def test_patch_order(self):
         "Test that dependent patches are tested in the right order"
         A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
diff --git a/zuul/ansible/library/zuul_console.py b/zuul/ansible/library/zuul_console.py
index e0d1d6e..42599d8 100644
--- a/zuul/ansible/library/zuul_console.py
+++ b/zuul/ansible/library/zuul_console.py
@@ -194,5 +194,6 @@
 
 from ansible.module_utils.basic import *  # noqa
 
-main()
+if __name__ == '__main__':
+    main()
 # test()
diff --git a/zuul/ansible/library/zuul_runner.py b/zuul/ansible/library/zuul_runner.py
index 955469f..bde4c16 100644
--- a/zuul/ansible/library/zuul_runner.py
+++ b/zuul/ansible/library/zuul_runner.py
@@ -71,4 +71,5 @@
 
 from ansible.module_utils.basic import *  # noqa
 
-main()
+if __name__ == '__main__':
+    main()
diff --git a/zuul/cmd/server.py b/zuul/cmd/server.py
index b1cd050..6db15a2 100755
--- a/zuul/cmd/server.py
+++ b/zuul/cmd/server.py
@@ -86,7 +86,8 @@
         import zuul.trigger.gerrit
 
         logging.basicConfig(level=logging.DEBUG)
-        self.sched = zuul.scheduler.Scheduler(self.config)
+        self.sched = zuul.scheduler.Scheduler(self.config,
+                                              testonly=True)
         self.configure_connections()
         layout = self.sched.testConfig(self.config.get('zuul',
                                                        'layout_config'),
diff --git a/zuul/connection/gerrit.py b/zuul/connection/gerrit.py
index 4671ff9..a1854f4 100644
--- a/zuul/connection/gerrit.py
+++ b/zuul/connection/gerrit.py
@@ -132,6 +132,7 @@
 
 class GerritWatcher(threading.Thread):
     log = logging.getLogger("gerrit.GerritWatcher")
+    poll_timeout = 500
 
     def __init__(self, gerrit_connection, username, hostname, port=29418,
                  keyfile=None):
@@ -154,7 +155,7 @@
         poll = select.poll()
         poll.register(stdout.channel)
         while not self._stopped:
-            ret = poll.poll()
+            ret = poll.poll(self.poll_timeout)
             for (fd, event) in ret:
                 if fd == stdout.channel.fileno():
                     if event == select.POLLIN:
diff --git a/zuul/launcher/ansiblelaunchserver.py b/zuul/launcher/ansiblelaunchserver.py
index d11a4af..6140c90 100644
--- a/zuul/launcher/ansiblelaunchserver.py
+++ b/zuul/launcher/ansiblelaunchserver.py
@@ -781,7 +781,7 @@
                                                        parameters, timeout))
             play = dict(hosts='node', name='Job body',
                         tasks=tasks)
-            playbook.write(yaml.dump([play]))
+            playbook.write(yaml.dump([play], default_flow_style=False))
 
         with open(jobdir.post_playbook, 'w') as playbook:
             tasks = []
@@ -794,7 +794,7 @@
                                                    parameters))
             play = dict(hosts='node', name='Publishers',
                         tasks=tasks)
-            playbook.write(yaml.dump([play]))
+            playbook.write(yaml.dump([play], default_flow_style=False))
 
         with open(jobdir.config, 'w') as config:
             config.write('[defaults]\n')
diff --git a/zuul/launcher/gearman.py b/zuul/launcher/gearman.py
index 69fb71b..f3b867c 100644
--- a/zuul/launcher/gearman.py
+++ b/zuul/launcher/gearman.py
@@ -456,9 +456,6 @@
                 build.number = data.get('number')
                 build.__gearman_manager = data.get('manager')
                 self.sched.onBuildStarted(build)
-
-            if job.denominator:
-                build.estimated_time = float(job.denominator) / 1000
         else:
             self.log.error("Unable to find build %s" % job.unique)
 
diff --git a/zuul/model.py b/zuul/model.py
index 5bea5d0..3fb0577 100644
--- a/zuul/model.py
+++ b/zuul/model.py
@@ -13,7 +13,9 @@
 # under the License.
 
 import copy
+import os
 import re
+import struct
 import time
 from uuid import uuid4
 import extras
@@ -1380,3 +1382,78 @@
                     job.copy(metajob)
             self.jobs[name] = job
         return job
+
+
+class JobTimeData(object):
+    format = 'B10H10H10B'
+    version = 0
+
+    def __init__(self, path):
+        self.path = path
+        self.success_times = [0 for x in range(10)]
+        self.failure_times = [0 for x in range(10)]
+        self.results = [0 for x in range(10)]
+
+    def load(self):
+        if not os.path.exists(self.path):
+            return
+        with open(self.path) as f:
+            data = struct.unpack(self.format, f.read())
+        version = data[0]
+        if version != self.version:
+            raise Exception("Unkown data version")
+        self.success_times = list(data[1:11])
+        self.failure_times = list(data[11:21])
+        self.results = list(data[21:32])
+
+    def save(self):
+        tmpfile = self.path + '.tmp'
+        data = [self.version]
+        data.extend(self.success_times)
+        data.extend(self.failure_times)
+        data.extend(self.results)
+        data = struct.pack(self.format, *data)
+        with open(tmpfile, 'w') as f:
+            f.write(data)
+        os.rename(tmpfile, self.path)
+
+    def add(self, elapsed, result):
+        elapsed = int(elapsed)
+        if result == 'SUCCESS':
+            self.success_times.append(elapsed)
+            self.success_times.pop(0)
+            result = 0
+        else:
+            self.failure_times.append(elapsed)
+            self.failure_times.pop(0)
+            result = 1
+        self.results.append(result)
+        self.results.pop(0)
+
+    def getEstimatedTime(self):
+        times = [x for x in self.success_times if x]
+        if times:
+            return float(sum(times)) / len(times)
+        return 0.0
+
+
+class TimeDataBase(object):
+    def __init__(self, root):
+        self.root = root
+        self.jobs = {}
+
+    def _getTD(self, name):
+        td = self.jobs.get(name)
+        if not td:
+            td = JobTimeData(os.path.join(self.root, name))
+            self.jobs[name] = td
+            td.load()
+        return td
+
+    def getEstimatedTime(self, name):
+        return self._getTD(name).getEstimatedTime()
+
+    def update(self, name, elapsed, result):
+        td = self._getTD(name)
+        td.add(elapsed, result)
+        td.save()
diff --git a/zuul/scheduler.py b/zuul/scheduler.py
index aea9a67..30a6c81 100644
--- a/zuul/scheduler.py
+++ b/zuul/scheduler.py
@@ -236,7 +236,7 @@
 class Scheduler(threading.Thread):
     log = logging.getLogger("zuul.Scheduler")
 
-    def __init__(self, config):
+    def __init__(self, config, testonly=False):
         threading.Thread.__init__(self)
         self.daemon = True
         self.wake_event = threading.Event()
@@ -262,6 +262,10 @@
         self.management_event_queue = Queue.Queue()
         self.layout = model.Layout()
 
+        if not testonly:
+            time_dir = self._get_time_database_dir()
+            self.time_database = model.TimeDataBase(time_dir)
+
         self.zuul_version = zuul_version.version_info.release_string()
         self.last_reconfigured = None
 
@@ -740,6 +744,17 @@
             state_dir = '/var/lib/zuul'
         return os.path.join(state_dir, 'queue.pickle')
 
+    def _get_time_database_dir(self):
+        if self.config.has_option('zuul', 'state_dir'):
+            state_dir = os.path.expanduser(self.config.get('zuul',
+                                                           'state_dir'))
+        else:
+            state_dir = '/var/lib/zuul'
+        d = os.path.join(state_dir, 'times')
+        if not os.path.exists(d):
+            os.mkdir(d)
+        return d
+
     def _save_queue(self):
         pickle_file = self._get_queue_pickle_file()
         events = []
@@ -1069,6 +1084,11 @@
             self.log.warning("Build %s is not associated with a pipeline" %
                              (build,))
             return
+        try:
+            build.estimated_time = float(self.time_database.getEstimatedTime(
+                build.job.name))
+        except Exception:
+            self.log.exception("Exception estimating build time:")
         pipeline.manager.onBuildStarted(event.build)
 
     def _doBuildCompletedEvent(self, event):
@@ -1082,6 +1102,12 @@
             self.log.warning("Build %s is not associated with a pipeline" %
                              (build,))
             return
+        if build.end_time and build.start_time and build.result:
+            duration = build.end_time - build.start_time
+        try:
+            self.time_database.update(build.job.name, duration, build.result)
+        except Exception:
+            self.log.exception("Exception recording build time:")
         pipeline.manager.onBuildCompleted(event.build)
 
     def _doMergeCompletedEvent(self, event):