Exposes new ksm config directive.

This change exposes the ksm config directive used
for enable/disable the KSM feature on the /e/d/qemu-kvm file.

- Updated templates/qemu-kvm
- Added tests for the new config option

Closes-Bug: #1670281

Change-Id: I24b44dc3e66d73c39fac0be0949be52710b571fd
Signed-off-by: Jorge Niedbalski <jorge.niedbalski@canonical.com>

config.yaml

@@ -226,18 +226,18 @@ options:
     type: string
     default:
     description: |
-      Set to 'host-model' to clone the host CPU feature flags; to 
-      'host-passthrough' to use the host CPU model exactly; to 'custom' to 
-      use a named CPU model; to 'none' to not set any CPU model. If 
-      virt_type='kvm|qemu', it will default to 'host-model', otherwise it will 
+      Set to 'host-model' to clone the host CPU feature flags; to
+      'host-passthrough' to use the host CPU model exactly; to 'custom' to
+      use a named CPU model; to 'none' to not set any CPU model. If
+      virt_type='kvm|qemu', it will default to 'host-model', otherwise it will
       default to 'none'.  Defaults to 'host-passthrough' for ppc64el, ppc64le
       if no value is set.
   cpu-model:
     type: string
     default:
     description: |
-      Set to a named libvirt CPU model (see names listed in 
-      /usr/share/libvirt/cpu_map.xml). Only has effect if cpu_mode='custom' and 
+      Set to a named libvirt CPU model (see names listed in
+      /usr/share/libvirt/cpu_map.xml). Only has effect if cpu_mode='custom' and
       virt_type='kvm|qemu'.
   # Storage configuration options
   libvirt-image-backend:
@@ -308,6 +308,13 @@ options:
       For a systemd system (wily and later) the prefered approach is to enable
       hugepages via kernel parameters set in MAAS and systemd will mount them
       automatically.
+  ksm:
+    type: string
+    default: "AUTO"
+    description: |
+      Set to 1 to enable KSM, 0 to disable KSM, and AUTO to use default settings.
+      Please note that the AUTO value works for qemu 2.2+ (> Kilo), older
+      releases will be set to 1 as default.
   action-managed-upgrade:
     type: boolean
     default: False

hooks/nova_compute_context.py

@@ -33,6 +33,7 @@ from charmhelpers.core.hookenv import (
     related_units,
     service_name,
     ERROR,
+    INFO,
 )
 from charmhelpers.contrib.openstack.utils import (
     get_os_version_package,
@@ -191,6 +192,16 @@ class NovaComputeLibvirtContext(context.OSContextGenerator):
         else:
             ctxt['kvm_hugepages'] = 0
 
+        if config('ksm') in ("1", "0",):
+            ctxt['ksm'] = config('ksm')
+        else:
+            if release < 'kilo':
+                log("KSM set to 1 by default on openstack releases < kilo",
+                    level=INFO)
+                ctxt['ksm'] = "1"
+            else:
+                ctxt['ksm'] = "AUTO"
+
         if config('pci-passthrough-whitelist'):
             ctxt['pci_passthrough_whitelist'] = \
                 config('pci-passthrough-whitelist')

templates/qemu-kvm

@@ -2,5 +2,15 @@
 # [ WARNING ]
 # Configuration file maintained by Juju. Local changes may be overwritten.
 ###############################################################################
+# Set to 1 to enable KSM, 0 to disable KSM, and AUTO to use default settings.
+# After changing this setting restart the qemu-kvm service.
+KSM_ENABLED={{ ksm }}
+SLEEP_MILLISECS=200
+# To load the vhost_net module, which in some cases can speed up
+# network performance, set VHOST_NET_ENABLED to 1.
+VHOST_NET_ENABLED=0
+
+# Set this to 1 if you want hugepages to be available to kvm under
+# /run/hugepages/kvm
 KVM_HUGEPAGES={{ kvm_hugepages }}
 

unit_tests/test_nova_compute_contexts.py

@@ -76,6 +76,7 @@ class NovaComputeContextTests(CharmTestCase):
 
     def setUp(self):
         super(NovaComputeContextTests, self).setUp(context, TO_PATCH)
+        self.os_release.return_value = 'kilo'
         self.relation_get.side_effect = self.test_relation.get
         self.config.side_effect = self.test_config.get
         self.log.side_effect = fake_log
@@ -202,6 +203,7 @@ class NovaComputeContextTests(CharmTestCase):
             {'libvirtd_opts': '',
              'libvirt_user': 'libvirt',
              'arch': platform.machine(),
+             'ksm': 'AUTO',
              'kvm_hugepages': 0,
              'listen_tls': 0,
              'host_uuid': self.host_uuid,
@@ -216,6 +218,7 @@ class NovaComputeContextTests(CharmTestCase):
             {'libvirtd_opts': '-d',
              'libvirt_user': 'libvirtd',
              'arch': platform.machine(),
+             'ksm': 'AUTO',
              'kvm_hugepages': 0,
              'listen_tls': 0,
              'host_uuid': self.host_uuid,
@@ -230,6 +233,7 @@ class NovaComputeContextTests(CharmTestCase):
             {'libvirtd_opts': '-d -l',
              'libvirt_user': 'libvirtd',
              'arch': platform.machine(),
+             'ksm': 'AUTO',
              'kvm_hugepages': 0,
              'listen_tls': 0,
              'host_uuid': self.host_uuid,
@@ -245,6 +249,7 @@ class NovaComputeContextTests(CharmTestCase):
              'libvirt_user': 'libvirtd',
              'disk_cachemodes': 'file=unsafe,block=none',
              'arch': platform.machine(),
+             'ksm': 'AUTO',
              'kvm_hugepages': 0,
              'listen_tls': 0,
              'host_uuid': self.host_uuid,
@@ -260,6 +265,7 @@ class NovaComputeContextTests(CharmTestCase):
              'libvirt_user': 'libvirtd',
              'arch': platform.machine(),
              'hugepages': True,
+             'ksm': 'AUTO',
              'kvm_hugepages': 1,
              'listen_tls': 0,
              'host_uuid': self.host_uuid,
@@ -342,6 +348,7 @@ class NovaComputeContextTests(CharmTestCase):
             {'libvirtd_opts': '-d',
              'libvirt_user': 'libvirtd',
              'arch': platform.machine(),
+             'ksm': 'AUTO',
              'hugepages': True,
              'kvm_hugepages': 1,
              'listen_tls': 0,
@@ -350,6 +357,38 @@ class NovaComputeContextTests(CharmTestCase):
              'vcpu_pin_set': '^0^2',
              'pci_passthrough_whitelist': 'mypcidevices'}, libvirt())
 
+    def test_ksm_configs(self):
+        self.test_config.set('ksm', '1')
+        libvirt = context.NovaComputeLibvirtContext()
+        self.assertTrue(libvirt()['ksm'] == '1')
+
+        self.test_config.set('ksm', '0')
+        libvirt = context.NovaComputeLibvirtContext()
+        self.assertTrue(libvirt()['ksm'] == '0')
+
+        self.test_config.set('ksm', 'AUTO')
+        libvirt = context.NovaComputeLibvirtContext()
+        self.assertTrue(libvirt()['ksm'] == 'AUTO')
+
+        self.test_config.set('ksm', '')
+        libvirt = context.NovaComputeLibvirtContext()
+        self.assertTrue(libvirt()['ksm'] == 'AUTO')
+
+        self.os_release.return_value = 'ocata'
+        self.test_config.set('ksm', 'AUTO')
+        libvirt = context.NovaComputeLibvirtContext()
+        self.assertTrue(libvirt()['ksm'] == 'AUTO')
+
+        self.os_release.return_value = 'kilo'
+        self.test_config.set('ksm', 'AUTO')
+        libvirt = context.NovaComputeLibvirtContext()
+        self.assertTrue(libvirt()['ksm'] == 'AUTO')
+
+        self.os_release.return_value = 'cactus'
+        self.test_config.set('ksm', 'AUTO')
+        libvirt = context.NovaComputeLibvirtContext()
+        self.assertTrue(libvirt()['ksm'] == '1')
+
     @patch.object(context.uuid, 'uuid4')
     def test_libvirt_cpu_mode_default(self, mock_uuid):
         libvirt = context.NovaComputeLibvirtContext()