Merge "cpu: interfaces for managing state and governor"

10 files changed, 466 insertions, 0 deletions

diff --git a/mypy-files.txt b/mypy-files.txt
index 5a3b9ab339..391ed58d87 100644
--- a/mypy-files.txt
+++ b/mypy-files.txt
@@ -1,6 +1,7 @@
 nova/compute/manager.py
 nova/compute/pci_placement_translator.py
 nova/crypto.py
+nova/filesystem.py
 nova/limit/local.py
 nova/limit/placement.py
 nova/network/neutron.py
@@ -13,6 +14,9 @@ nova/virt/driver.py
 nova/virt/hardware.py
 nova/virt/libvirt/machine_type_utils.py
 nova/virt/libvirt/__init__.py
+nova/virt/libvirt/cpu/__init__.py
+nova/virt/libvirt/cpu/api.py
+nova/virt/libvirt/cpu/core.py
 nova/virt/libvirt/driver.py
 nova/virt/libvirt/event.py
 nova/virt/libvirt/guest.py
diff --git a/nova/conf/libvirt.py b/nova/conf/libvirt.py
index 16a3f63090..632bba40fb 100644
--- a/nova/conf/libvirt.py
+++ b/nova/conf/libvirt.py
@@ -1478,6 +1478,15 @@ Related options:
 """),
 ]
 
+libvirt_cpu_mgmt_opts = [
+    cfg.StrOpt('cpu_power_governor_low',
+               default='powersave',
+               help='Governor to use in order '
+                    'to reduce CPU power consumption'),
+    cfg.StrOpt('cpu_power_governor_high',
+             default='performance',
+             help='Governor to use in order to have best CPU performance'),
+]
 
 ALL_OPTS = list(itertools.chain(
     libvirt_general_opts,
@@ -1499,6 +1508,7 @@ ALL_OPTS = list(itertools.chain(
     libvirt_volume_nvmeof_opts,
     libvirt_pmem_opts,
     libvirt_vtpm_opts,
+    libvirt_cpu_mgmt_opts,
 ))
 
 
diff --git a/nova/filesystem.py b/nova/filesystem.py
new file mode 100644
index 0000000000..5394d2d835
--- /dev/null
+++ b/nova/filesystem.py
@@ -0,0 +1,59 @@
+#    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.
+
+"""Functions to address filesystem calls, particularly sysfs."""
+
+import os
+
+from oslo_log import log as logging
+
+from nova import exception
+
+LOG = logging.getLogger(__name__)
+
+
+SYS = '/sys'
+
+
+# NOTE(bauzas): this method is deliberately not wrapped in a privsep entrypoint
+def read_sys(path: str) -> str:
+    """Reads the content of a file in the sys filesystem.
+
+    :param path: relative or absolute. If relative, will be prefixed by /sys.
+    :returns: contents of that file.
+    :raises: nova.exception.FileNotFound if we can't read that file.
+    """
+    try:
+        # The path can be absolute with a /sys prefix but that's fine.
+        with open(os.path.join(SYS, path), mode='r') as data:
+            return data.read()
+    except (OSError, ValueError) as exc:
+        raise exception.FileNotFound(file_path=path) from exc
+
+
+# NOTE(bauzas): this method is deliberately not wrapped in a privsep entrypoint
+# In order to correctly use it, you need to decorate the caller with a specific
+# privsep entrypoint.
+def write_sys(path: str, data: str) -> None:
+    """Writes the content of a file in the sys filesystem with data.
+
+    :param path: relative or absolute. If relative, will be prefixed by /sys.
+    :param data: the data to write.
+    :returns: contents of that file.
+    :raises: nova.exception.FileNotFound if we can't write that file.
+    """
+    try:
+        # The path can be absolute with a /sys prefix but that's fine.
+        with open(os.path.join(SYS, path), mode='w') as fd:
+            fd.write(data)
+    except (OSError, ValueError) as exc:
+        raise exception.FileNotFound(file_path=path) from exc
diff --git a/nova/tests/unit/test_filesystem.py b/nova/tests/unit/test_filesystem.py
new file mode 100644
index 0000000000..85f16157ee
--- /dev/null
+++ b/nova/tests/unit/test_filesystem.py
@@ -0,0 +1,52 @@
+#    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.
+
+import os
+from unittest import mock
+
+from nova import exception
+from nova import filesystem
+from nova import test
+
+
+class TestFSCommon(test.NoDBTestCase):
+
+    def test_read_sys(self):
+        open_mock = mock.mock_open(read_data='bar')
+        with mock.patch('builtins.open', open_mock) as m_open:
+            self.assertEqual('bar', filesystem.read_sys('foo'))
+        expected_path = os.path.join(filesystem.SYS, 'foo')
+        m_open.assert_called_once_with(expected_path, mode='r')
+
+    def test_read_sys_error(self):
+        with mock.patch('builtins.open',
+                        side_effect=OSError('error')) as m_open:
+            self.assertRaises(exception.FileNotFound,
+                              filesystem.read_sys, 'foo')
+        expected_path = os.path.join(filesystem.SYS, 'foo')
+        m_open.assert_called_once_with(expected_path, mode='r')
+
+    def test_write_sys(self):
+        open_mock = mock.mock_open()
+        with mock.patch('builtins.open', open_mock) as m_open:
+            self.assertIsNone(filesystem.write_sys('foo', 'bar'))
+        expected_path = os.path.join(filesystem.SYS, 'foo')
+        m_open.assert_called_once_with(expected_path, mode='w')
+        open_mock().write.assert_called_once_with('bar')
+
+    def test_write_sys_error(self):
+        with mock.patch('builtins.open',
+                        side_effect=OSError('fake_error')) as m_open:
+            self.assertRaises(exception.FileNotFound,
+                              filesystem.write_sys, 'foo', 'bar')
+        expected_path = os.path.join(filesystem.SYS, 'foo')
+        m_open.assert_called_once_with(expected_path, mode='w')
diff --git a/nova/tests/unit/virt/libvirt/cpu/__init__.py b/nova/tests/unit/virt/libvirt/cpu/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/nova/tests/unit/virt/libvirt/cpu/__init__.py
diff --git a/nova/tests/unit/virt/libvirt/cpu/test_api.py b/nova/tests/unit/virt/libvirt/cpu/test_api.py
new file mode 100644
index 0000000000..d47b3690a3
--- /dev/null
+++ b/nova/tests/unit/virt/libvirt/cpu/test_api.py
@@ -0,0 +1,63 @@
+#    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.
+
+from unittest import mock
+
+from nova import test
+from nova.virt.libvirt.cpu import api
+from nova.virt.libvirt.cpu import core
+
+
+class TestAPI(test.NoDBTestCase):
+
+    def setUp(self):
+        super(TestAPI, self).setUp()
+        self.core_1 = api.Core(1)
+
+    @mock.patch.object(core, 'get_online')
+    def test_online(self, mock_get_online):
+        mock_get_online.return_value = True
+        self.assertTrue(self.core_1.online)
+        mock_get_online.assert_called_once_with(self.core_1.ident)
+
+    @mock.patch.object(core, 'set_online')
+    def test_set_online(self, mock_set_online):
+        self.core_1.online = True
+        mock_set_online.assert_called_once_with(self.core_1.ident)
+
+    @mock.patch.object(core, 'set_offline')
+    def test_set_offline(self, mock_set_offline):
+        self.core_1.online = False
+        mock_set_offline.assert_called_once_with(self.core_1.ident)
+
+    def test_hash(self):
+        self.assertEqual(hash(self.core_1.ident), hash(self.core_1))
+
+    @mock.patch.object(core, 'get_governor')
+    def test_governor(self, mock_get_governor):
+        mock_get_governor.return_value = 'fake_governor'
+        self.assertEqual('fake_governor', self.core_1.governor)
+        mock_get_governor.assert_called_once_with(self.core_1.ident)
+
+    @mock.patch.object(core, 'set_governor')
+    def test_set_governor_low(self, mock_set_governor):
+        self.flags(cpu_power_governor_low='fake_low_gov', group='libvirt')
+        self.core_1.set_low_governor()
+        mock_set_governor.assert_called_once_with(self.core_1.ident,
+                                                  'fake_low_gov')
+
+    @mock.patch.object(core, 'set_governor')
+    def test_set_governor_high(self, mock_set_governor):
+        self.flags(cpu_power_governor_high='fake_high_gov', group='libvirt')
+        self.core_1.set_high_governor()
+        mock_set_governor.assert_called_once_with(self.core_1.ident,
+                                                  'fake_high_gov')
diff --git a/nova/tests/unit/virt/libvirt/cpu/test_core.py b/nova/tests/unit/virt/libvirt/cpu/test_core.py
new file mode 100644
index 0000000000..a3cba00d3b
--- /dev/null
+++ b/nova/tests/unit/virt/libvirt/cpu/test_core.py
@@ -0,0 +1,122 @@
+#    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.
+
+from unittest import mock
+
+from nova import exception
+from nova import test
+from nova.tests import fixtures
+from nova.virt.libvirt.cpu import core
+
+
+class TestCore(test.NoDBTestCase):
+
+    @mock.patch.object(core.filesystem, 'read_sys')
+    @mock.patch.object(core.hardware, 'parse_cpu_spec')
+    def test_get_available_cores(self, mock_parse_cpu_spec, mock_read_sys):
+        mock_read_sys.return_value = '1-2'
+        mock_parse_cpu_spec.return_value = set([1, 2])
+        self.assertEqual(set([1, 2]), core.get_available_cores())
+        mock_read_sys.assert_called_once_with(core.AVAILABLE_PATH)
+        mock_parse_cpu_spec.assert_called_once_with('1-2')
+
+    @mock.patch.object(core.filesystem, 'read_sys')
+    @mock.patch.object(core.hardware, 'parse_cpu_spec')
+    def test_get_available_cores_none(
+            self, mock_parse_cpu_spec, mock_read_sys):
+        mock_read_sys.return_value = ''
+        self.assertEqual(set(), core.get_available_cores())
+        mock_parse_cpu_spec.assert_not_called()
+
+    @mock.patch.object(core, 'get_available_cores')
+    def test_exists(self, mock_get_available_cores):
+        mock_get_available_cores.return_value = set([1])
+        self.assertTrue(core.exists(1))
+        mock_get_available_cores.assert_called_once_with()
+        self.assertFalse(core.exists(2))
+
+    @mock.patch.object(
+            core, 'CPU_PATH_TEMPLATE',
+            new_callable=mock.PropertyMock(return_value='/sys/blah%(core)s'))
+    @mock.patch.object(core, 'exists')
+    def test_gen_cpu_path(self, mock_exists, mock_cpu_path):
+        mock_exists.return_value = True
+        self.assertEqual('/sys/blah1', core.gen_cpu_path(1))
+        mock_exists.assert_called_once_with(1)
+
+    @mock.patch.object(core, 'exists')
+    def test_gen_cpu_path_raises(self, mock_exists):
+        mock_exists.return_value = False
+        self.assertRaises(ValueError, core.gen_cpu_path, 1)
+        self.assertIn('Unable to access CPU: 1', self.stdlog.logger.output)
+
+
+class TestCoreHelpers(test.NoDBTestCase):
+
+    def setUp(self):
+        super(TestCoreHelpers, self).setUp()
+        self.useFixture(fixtures.PrivsepFixture())
+        _p1 = mock.patch.object(core, 'exists', return_value=True)
+        self.mock_exists = _p1.start()
+        self.addCleanup(_p1.stop)
+
+        _p2 = mock.patch.object(core, 'gen_cpu_path',
+                                side_effect=lambda x: '/fakesys/blah%s' % x)
+        self.mock_gen_cpu_path = _p2.start()
+        self.addCleanup(_p2.stop)
+
+    @mock.patch.object(core.filesystem, 'read_sys')
+    def test_get_online(self, mock_read_sys):
+        mock_read_sys.return_value = '1'
+        self.assertTrue(core.get_online(1))
+        mock_read_sys.assert_called_once_with('/fakesys/blah1/online')
+
+    @mock.patch.object(core.filesystem, 'read_sys')
+    def test_get_online_not_exists(self, mock_read_sys):
+        mock_read_sys.side_effect = exception.FileNotFound(file_path='foo')
+        self.assertTrue(core.get_online(1))
+        mock_read_sys.assert_called_once_with('/fakesys/blah1/online')
+
+    @mock.patch.object(core.filesystem, 'write_sys')
+    @mock.patch.object(core, 'get_online')
+    def test_set_online(self, mock_get_online, mock_write_sys):
+        mock_get_online.return_value = True
+        self.assertTrue(core.set_online(1))
+        mock_write_sys.assert_called_once_with('/fakesys/blah1/online',
+                                               data='1')
+        mock_get_online.assert_called_once_with(1)
+
+    @mock.patch.object(core.filesystem, 'write_sys')
+    @mock.patch.object(core, 'get_online')
+    def test_set_offline(self, mock_get_online, mock_write_sys):
+        mock_get_online.return_value = False
+        self.assertTrue(core.set_offline(1))
+        mock_write_sys.assert_called_once_with('/fakesys/blah1/online',
+                                               data='0')
+        mock_get_online.assert_called_once_with(1)
+
+    @mock.patch.object(core.filesystem, 'read_sys')
+    def test_get_governor(self, mock_read_sys):
+        mock_read_sys.return_value = 'fake_gov'
+        self.assertEqual('fake_gov', core.get_governor(1))
+        mock_read_sys.assert_called_once_with(
+            '/fakesys/blah1/cpufreq/scaling_governor')
+
+    @mock.patch.object(core, 'get_governor')
+    @mock.patch.object(core.filesystem, 'write_sys')
+    def test_set_governor(self, mock_write_sys, mock_get_governor):
+        mock_get_governor.return_value = 'fake_gov'
+        self.assertEqual('fake_gov',
+                         core.set_governor(1, 'fake_gov'))
+        mock_write_sys.assert_called_once_with(
+            '/fakesys/blah1/cpufreq/scaling_governor', data='fake_gov')
+        mock_get_governor.assert_called_once_with(1)
diff --git a/nova/virt/libvirt/cpu/__init__.py b/nova/virt/libvirt/cpu/__init__.py
new file mode 100644
index 0000000000..962c9469a0
--- /dev/null
+++ b/nova/virt/libvirt/cpu/__init__.py
@@ -0,0 +1,16 @@
+#    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.
+
+from nova.virt.libvirt.cpu import api
+
+
+Core = api.Core
diff --git a/nova/virt/libvirt/cpu/api.py b/nova/virt/libvirt/cpu/api.py
new file mode 100644
index 0000000000..e0b0a277d1
--- /dev/null
+++ b/nova/virt/libvirt/cpu/api.py
@@ -0,0 +1,62 @@
+#    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.
+
+from dataclasses import dataclass
+
+from oslo_log import log as logging
+
+import nova.conf
+from nova.virt.libvirt.cpu import core
+
+LOG = logging.getLogger(__name__)
+
+CONF = nova.conf.CONF
+
+
+@dataclass
+class Core:
+    """Class to model a CPU core as reported by sysfs.
+
+    It may be a physical CPU core or a hardware thread on a shared CPU core
+    depending on if the system supports SMT.
+    """
+
+    # NOTE(sbauza): ident is a mandatory field.
+    # The CPU core id/number
+    ident: int
+
+    @property
+    def online(self) -> bool:
+        return core.get_online(self.ident)
+
+    @online.setter
+    def online(self, state: bool) -> None:
+        if state:
+            core.set_online(self.ident)
+        else:
+            core.set_offline(self.ident)
+
+    def __hash__(self):
+        return hash(self.ident)
+
+    def __eq__(self, other):
+        return self.ident == other.ident
+
+    @property
+    def governor(self) -> str:
+        return core.get_governor(self.ident)
+
+    def set_high_governor(self) -> None:
+        core.set_governor(self.ident, CONF.libvirt.cpu_power_governor_high)
+
+    def set_low_governor(self) -> None:
+        core.set_governor(self.ident, CONF.libvirt.cpu_power_governor_low)
diff --git a/nova/virt/libvirt/cpu/core.py b/nova/virt/libvirt/cpu/core.py
new file mode 100644
index 0000000000..782f028fee
--- /dev/null
+++ b/nova/virt/libvirt/cpu/core.py
@@ -0,0 +1,78 @@
+#    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.
+
+import os
+import typing as ty
+
+from oslo_log import log as logging
+
+from nova import exception
+from nova import filesystem
+import nova.privsep
+from nova.virt import hardware
+
+LOG = logging.getLogger(__name__)
+
+AVAILABLE_PATH = '/sys/devices/system/cpu/present'
+
+CPU_PATH_TEMPLATE = '/sys/devices/system/cpu/cpu%(core)s'
+
+
+def get_available_cores() -> ty.Set[int]:
+    cores = filesystem.read_sys(AVAILABLE_PATH)
+    return hardware.parse_cpu_spec(cores) if cores else set()
+
+
+def exists(core: int) -> bool:
+    return core in get_available_cores()
+
+
+def gen_cpu_path(core: int) -> str:
+    if not exists(core):
+        LOG.warning('Unable to access CPU: %s', core)
+        raise ValueError('CPU: %(core)s does not exist', core)
+    return CPU_PATH_TEMPLATE % {'core': core}
+
+
+def get_online(core: int) -> bool:
+    try:
+        online = filesystem.read_sys(
+            os.path.join(gen_cpu_path(core), 'online')).strip()
+    except exception.FileNotFound:
+        # The online file may not exist if we haven't written it yet.
+        # By default, this means that the CPU is online.
+        online = '1'
+    return online == '1'
+
+
+@nova.privsep.sys_admin_pctxt.entrypoint
+def set_online(core: int) -> bool:
+    filesystem.write_sys(os.path.join(gen_cpu_path(core), 'online'), data='1')
+    return get_online(core)
+
+
+def set_offline(core: int) -> bool:
+    filesystem.write_sys(os.path.join(gen_cpu_path(core), 'online'), data='0')
+    return not get_online(core)
+
+
+def get_governor(core: int) -> str:
+    return filesystem.read_sys(
+        os.path.join(gen_cpu_path(core), 'cpufreq/scaling_governor')).strip()
+
+
+@nova.privsep.sys_admin_pctxt.entrypoint
+def set_governor(core: int, governor: str) -> str:
+    filesystem.write_sys(
+        os.path.join(gen_cpu_path(core), 'cpufreq/scaling_governor'),
+        data=governor)
+    return get_governor(core)