Use vcpu.x.time and vcpu.x.wait values in libvirt inspector

If possible, calculate cputime from vcpu time + vcpu wait.
Fall back to cpu.time, if any vcpu.x.time or vcpu.x.wait
values are missing.
derived from I7bce33854dfe9c7b0e03b8c22721d04028183701

Co-Authored-By: Michael Ly <msly@us.ibm.com>
Co-Authored-By: Avi Weit <WEIT@il.ibm.com>
Co-Authored-By: Jorge Rodriguez <jorgedr@us.ibm.com>
Co-Authored-By: Karolyn Chambers <Karolyn.Chambers@target.com>
Co-Authored-By: Daniel Berrange <berrange@redhat.com>
Co-Authored-By: gordon chung <gord@live.ca>

Change-Id: I20700a32d608b3444b22c5ae460002eeb86d78ae
Closes-bug: #1677159
Closes-bug: #1421584

ceilometer/compute/virt/libvirt/inspector.py

@@ -173,10 +173,30 @@ class LibvirtInspector(virt_inspector.Inspector):
         # TODO(sileht): stats also have the disk/vnic info
         # we could use that instead of the old method for Queen
         stats = self.connection.domainListGetStats([domain], 0)[0][1]
+        cpu_time = 0
+        current_cpus = stats.get('vcpu.current')
+        # Iterate over the maximum number of CPUs here, and count the
+        # actual number encountered, since the vcpu.x structure can
+        # have holes according to
+        # https://libvirt.org/git/?p=libvirt.git;a=blob;f=src/libvirt-domain.c
+        # virConnectGetAllDomainStats()
+        for vcpu in six.moves.range(stats.get('vcpu.maximum', 0)):
+            try:
+                cpu_time += (stats.get('vcpu.%s.time' % vcpu) +
+                             stats.get('vcpu.%s.wait' % vcpu))
+                current_cpus -= 1
+            except TypeError:
+                # pass here, if there are too many holes, the cpu count will
+                # not match, so don't need special error handling.
+                pass
+
+        if current_cpus:
+            # There wasn't enough data, so fall back
+            cpu_time = stats.get('cpu.time')
 
         return virt_inspector.InstanceStats(
             cpu_number=stats.get('vcpu.current'),
-            cpu_time=stats.get('cpu.time'),
+            cpu_time=cpu_time,
             memory_usage=memory_used,
             memory_resident=memory_resident,
             cpu_cycles=stats.get("perf.cpu_cycles"),

ceilometer/tests/unit/compute/virt/libvirt/test_inspector.py

@@ -60,7 +60,12 @@ class TestLibvirtInspection(base.BaseTestCase):
         conn.lookupByUUIDString.return_value = domain
         conn.domainListGetStats.return_value = [({}, {
             'cpu.time': 999999,
+            'vcpu.maximum': 4,
             'vcpu.current': 2,
+            'vcpu.0.time': 10000,
+            'vcpu.0.wait': 10000,
+            'vcpu.2.time': 10000,
+            'vcpu.2.wait': 10000,
             'perf.cmt': 90112,
             'perf.cpu_cycles': 7259361,
             'perf.instructions': 8815623,
@@ -73,7 +78,7 @@ class TestLibvirtInspection(base.BaseTestCase):
                         'refresh_libvirt_connection', return_value=conn):
             stats = self.inspector.inspect_instance(self.instance)
             self.assertEqual(2, stats.cpu_number)
-            self.assertEqual(999999, stats.cpu_time)
+            self.assertEqual(40000, stats.cpu_time)
             self.assertEqual(90112, stats.cpu_l3_cache_usage)
             self.assertEqual(25600 / units.Ki, stats.memory_usage)
             self.assertEqual(30000 / units.Ki, stats.memory_resident)
@@ -84,6 +89,27 @@ class TestLibvirtInspection(base.BaseTestCase):
             self.assertEqual(74184, stats.cache_references)
             self.assertEqual(16737, stats.cache_misses)
 
+    def test_inspect_instance_stats_fallback_cpu_time(self):
+        domain = mock.Mock()
+        domain.info.return_value = (0, 0, 0, 2, 20000)
+        domain.memoryStats.return_value = {'available': 51200,
+                                           'unused': 25600,
+                                           'rss': 30000}
+        conn = mock.Mock()
+        conn.lookupByUUIDString.return_value = domain
+        conn.domainListGetStats.return_value = [({}, {
+            'vcpu.current': 2,
+            'vcpu.maximum': 4,
+            'vcpu.0.time': 10000,
+            'vcpu.1.time': 10000,
+            'cpu.time': 999999})]
+
+        with mock.patch('ceilometer.compute.virt.libvirt.utils.'
+                        'refresh_libvirt_connection', return_value=conn):
+            stats = self.inspector.inspect_instance(self.instance)
+            self.assertEqual(2, stats.cpu_number)
+            self.assertEqual(999999, stats.cpu_time)
+
     def test_inspect_cpus_with_domain_shutoff(self):
         domain = mock.Mock()
         domain.info.return_value = (5, 0, 0, 2, 999999)