Libvirt: Correct PERF_EVENTS_CPU_FLAG_MAPPING

History:

libvirt 1.3.3 had added perf event support for cmt, mbmt, mbml support
when we landing the spec
https://blueprints.launchpad.net/nova/+spec/support-perf-event .

For the event cmt, mbmt, mbml, we requires that libvirt to expose some
some specify cpu features, but libvirt 2.0.0 only has that expose merged
`cpu_map.xml: add cmt/mbm feature to x86 (Qiaowei Ren)`, the capabilities
changed to:

<feature name='mbm_total'/>
<feature name='mbm_local'/>
<feature name='cmt'/>

Need to adopt this to let nova driver discover these features when
enable cmt, mbmt, mbml event.

That is to say: even libvirt 1.3.3 has support perf event, but nova
cannot get noticed since libvirt don't expose cpu features until 2.0.0.

This patch bump MIN_LIBVIRT_PERF_VERSION to 2.0.0, see:
https://libvirt.org/formatdomain.html#elementsPerf

Closes-Bug: #1620445
Change-Id: Ie896cfd478f4528903ca5dd56c61680837b646b7

nova/conf/libvirt.py

@@ -448,7 +448,8 @@ Related options:
 This is a performance event list which could be used as monitor. These events
 will be passed to libvirt domain xml while creating a new instances.
 Then event statistics data can be collected from libvirt.  The minimum
-libvirt version is 1.3.3.
+libvirt version is 2.0.0. For more information about `Performance monitoring
+events`, refer https://libvirt.org/formatdomain.html#elementsPerf .
 
 * Possible values:
     A string list.

nova/tests/unit/virt/libvirt/test_driver.py

@@ -5623,7 +5623,6 @@ class LibvirtConnTestCase(test.NoDBTestCase):
 
     @mock.patch.object(host.Host, "get_capabilities")
     def _test_get_guest_with_perf(self, caps, events, mock_get_caps):
-        self.flags(enabled_perf_events=['cmt'], group='libvirt')
         mock_get_caps.return_value = caps
 
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
@@ -5641,21 +5640,31 @@ class LibvirtConnTestCase(test.NoDBTestCase):
 
     @mock.patch.object(fakelibvirt, 'VIR_PERF_PARAM_CMT', True,
                        create=True)
+    @mock.patch.object(fakelibvirt, 'VIR_PERF_PARAM_MBMT', True,
+                       create=True)
+    @mock.patch.object(fakelibvirt, 'VIR_PERF_PARAM_MBML', True,
+                       create=True)
     @mock.patch.object(host.Host, 'has_min_version', return_value=True)
     def test_get_guest_with_perf_supported(self,
                                  mock_min_version):
-        self.flags(enabled_perf_events=['cmt'], group='libvirt')
+        self.flags(enabled_perf_events=['cmt', 'mbml', 'mbmt'],
+                   group='libvirt')
         caps = vconfig.LibvirtConfigCaps()
         caps.host = vconfig.LibvirtConfigCapsHost()
         caps.host.cpu = vconfig.LibvirtConfigCPU()
         caps.host.cpu.arch = "x86_64"
         caps.host.topology = self._fake_caps_numa_topology()
-        feature = vconfig.LibvirtConfigGuestCPUFeature()
-        feature.name = 'cqm'
-        feature.policy = cpumodel.POLICY_REQUIRE
-        caps.host.cpu.features = set([feature])
 
-        self._test_get_guest_with_perf(caps, ['cmt'])
+        features = []
+        for f in ('cmt', 'mbm_local', 'mbm_total'):
+            feature = vconfig.LibvirtConfigGuestCPUFeature()
+            feature.name = f
+            feature.policy = cpumodel.POLICY_REQUIRE
+            features.append(feature)
+
+        caps.host.cpu.features = set(features)
+
+        self._test_get_guest_with_perf(caps, ['cmt', 'mbml', 'mbmt'])
 
     @mock.patch.object(host.Host, 'has_min_version')
     def test_get_guest_with_perf_libvirt_unsupported(self, mock_min_version):

nova/virt/libvirt/driver.py

@@ -310,12 +310,12 @@ MIN_QEMU_OTHER_ARCH = {arch.S390: MIN_QEMU_S390_VERSION,
                       }
 
 # perf events support
-MIN_LIBVIRT_PERF_VERSION = (1, 3, 3)
+MIN_LIBVIRT_PERF_VERSION = (2, 0, 0)
 LIBVIRT_PERF_EVENT_PREFIX = 'VIR_PERF_PARAM_'
 
-PERF_EVENTS_CPU_FLAG_MAPPING = {'cmt': 'cqm',
+PERF_EVENTS_CPU_FLAG_MAPPING = {'cmt': 'cmt',
-                                'mbml': 'cqm_mbm_local',
+                                'mbml': 'mbm_local',
-                                'mbmt': 'cqm_mbm_total',
+                                'mbmt': 'mbm_total',
                                }
 
 

releasenotes/notes/add-perf-event-e1385b6b6346fbda.yaml

@@ -3,4 +3,4 @@ features:
   - Add perf event support for libvirt driver.
     This can be done by adding new configure option
     'enabled_perf_events' in libvirt section of
-    nova.conf. This feature requires libvirt>=1.3.3.
+    nova.conf. This feature requires libvirt>=2.0.0.