Arnike/watcher
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
8d2c249f4bacadb6d61b0f8b32ae499189b5fcf0
watcher/watcher/decision_engine/strategy/strategies/vm_workload_consolidation.py
Dantali0n b24bd7a3bb Generalize exceptions & structure of strategies 
Many strategies execute very similar statements especially in
pre_execute and some might raise errors that others might not. This
same pattern of many similar statements can also be observed in
strategies their tests.

This patch addresses these issues, firstly; the BaseStrategy class gets
1 additional method _pre_execute which allows for general logic that
most strategies perform at that stage. This method can be executed
before the similarly named method of the superclass. A notable change
is that _pre_execute now handles common exception handling for
ClusterStateStale & ClusterStateNotDefined exceptions.

A similar pattern is applied to the test classes of the strategies
each of these classes now inherits from the TestBaseStrategy class.
This class provides the common attributes almost every test class for
the strategies requires such as: The mocked compute_model, mocked
audit_scope and an instance of FakerModelCollector.

Finally, some minor changes were required in test_strategy_context
& test_audit_handlers and exceptions around 0 nodes in cluster or
storage are removed.

Change-Id: Ia7154376b2448aac65cf17999cc8c3e1c8309b5b
2019-03-08 08:14:48 +01:00

613 lines
24 KiB
Python
Raw Blame History

# -*- encoding: utf-8 -*-
#
# Authors: Vojtech CIMA <cima@zhaw.ch>
# Bruno GRAZIOLI <gaea@zhaw.ch>
# Sean MURPHY <murp@zhaw.ch>
#
# 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 oslo_config import cfg
from oslo_log import log
import six
from watcher._i18n import _
from watcher.common import exception
from watcher.decision_engine.model import element
from watcher.decision_engine.strategy.strategies import base
LOG = log.getLogger(__name__)
class VMWorkloadConsolidation(base.ServerConsolidationBaseStrategy):
"""VM Workload Consolidation Strategy
A load consolidation strategy based on heuristic first-fit
algorithm which focuses on measured CPU utilization and tries to
minimize hosts which have too much or too little load respecting
resource capacity constraints.
This strategy produces a solution resulting in more efficient
utilization of cluster resources using following four phases:
* Offload phase - handling over-utilized resources
* Consolidation phase - handling under-utilized resources
* Solution optimization - reducing number of migrations
* Disability of unused compute nodes
A capacity coefficients (cc) might be used to adjust optimization
thresholds. Different resources may require different coefficient
values as well as setting up different coefficient values in both
phases may lead to to more efficient consolidation in the end.
If the cc equals 1 the full resource capacity may be used, cc
values lower than 1 will lead to resource under utilization and
values higher than 1 will lead to resource overbooking.
e.g. If targeted utilization is 80 percent of a compute node capacity,
the coefficient in the consolidation phase will be 0.8, but
may any lower value in the offloading phase. The lower it gets
the cluster will appear more released (distributed) for the
following consolidation phase.
As this strategy leverages VM live migration to move the load
from one compute node to another, this feature needs to be set up
correctly on all compute nodes within the cluster.
This strategy assumes it is possible to live migrate any VM from
an active compute node to any other active compute node.
"""
HOST_CPU_USAGE_METRIC_NAME = 'compute.node.cpu.percent'
INSTANCE_CPU_USAGE_METRIC_NAME = 'cpu_util'
AGGREGATION = 'mean'
DATASOURCE_METRICS = ['instance_ram_allocated', 'instance_cpu_usage',
'instance_ram_usage', 'instance_root_disk_size']
METRIC_NAMES = dict(
ceilometer=dict(
cpu_util_metric='cpu_util',
ram_util_metric='memory.resident',
ram_alloc_metric='memory',
disk_alloc_metric='disk.root.size'),
gnocchi=dict(
cpu_util_metric='cpu_util',
ram_util_metric='memory.resident',
ram_alloc_metric='memory',
disk_alloc_metric='disk.root.size'),
)
MIGRATION = "migrate"
CHANGE_NOVA_SERVICE_STATE = "change_nova_service_state"
def __init__(self, config, osc=None):
super(VMWorkloadConsolidation, self).__init__(config, osc)
self._ceilometer = None
self._gnocchi = None
self.number_of_migrations = 0
self.number_of_released_nodes = 0
# self.ceilometer_instance_data_cache = dict()
self.datasource_instance_data_cache = dict()
@classmethod
def get_name(cls):
return "vm_workload_consolidation"
@classmethod
def get_display_name(cls):
return _("VM Workload Consolidation Strategy")
@classmethod
def get_translatable_display_name(cls):
return "VM Workload Consolidation Strategy"
@property
def period(self):
return self.input_parameters.get('period', 3600)
@property
def granularity(self):
return self.input_parameters.get('granularity', 300)
@classmethod
def get_schema(cls):
# Mandatory default setting for each element
return {
"properties": {
"period": {
"description": "The time interval in seconds for "
"getting statistic aggregation",
"type": "number",
"default": 3600
},
"granularity": {
"description": "The time between two measures in an "
"aggregated timeseries of a metric.",
"type": "number",
"default": 300
},
}
}
@classmethod
def get_config_opts(cls):
return [
cfg.ListOpt(
"datasources",
help="Datasources to use in order to query the needed metrics."
" If one of strategy metric isn't available in the first"
" datasource, the next datasource will be chosen.",
item_type=cfg.types.String(choices=['gnocchi', 'ceilometer',
'monasca']),
default=['gnocchi', 'ceilometer', 'monasca'])
]
def get_available_compute_nodes(self):
default_node_scope = [element.ServiceState.ENABLED.value,
element.ServiceState.DISABLED.value]
nodes = self.compute_model.get_all_compute_nodes().items()
return {uuid: cn for uuid, cn in
nodes
if cn.state == element.ServiceState.ONLINE.value and
cn.status in default_node_scope}
def get_instance_state_str(self, instance):
"""Get instance state in string format.
:param instance:
"""
if isinstance(instance.state, six.string_types):
return instance.state
elif isinstance(instance.state, element.InstanceState):
return instance.state.value
else:
LOG.error('Unexpected instance state type, '
'state=%(state)s, state_type=%(st)s.',
dict(state=instance.state,
st=type(instance.state)))
raise exception.WatcherException
def get_node_status_str(self, node):
"""Get node status in string format.
:param node:
"""
if isinstance(node.status, six.string_types):
return node.status
elif isinstance(node.status, element.ServiceState):
return node.status.value
else:
LOG.error('Unexpected node status type, '
'status=%(status)s, status_type=%(st)s.',
dict(status=node.status,
st=type(node.status)))
raise exception.WatcherException
def add_action_enable_compute_node(self, node):
"""Add an action for node enabler into the solution.
:param node: node object
:return: None
"""
params = {'state': element.ServiceState.ENABLED.value}
self.solution.add_action(
action_type=self.CHANGE_NOVA_SERVICE_STATE,
resource_id=node.uuid,
input_parameters=params)
self.number_of_released_nodes -= 1
def add_action_disable_node(self, node):
"""Add an action for node disability into the solution.
:param node: node object
:return: None
"""
params = {'state': element.ServiceState.DISABLED.value,
'disabled_reason': self.REASON_FOR_DISABLE}
self.solution.add_action(
action_type=self.CHANGE_NOVA_SERVICE_STATE,
resource_id=node.uuid,
input_parameters=params)
self.number_of_released_nodes += 1
def add_migration(self, instance, source_node, destination_node):
"""Add an action for VM migration into the solution.
:param instance: instance object
:param source_node: node object
:param destination_node: node object
:return: None
"""
instance_state_str = self.get_instance_state_str(instance)
if instance_state_str not in (element.InstanceState.ACTIVE.value,
element.InstanceState.PAUSED.value):
# Watcher currently only supports live VM migration and block live
# VM migration which both requires migrated VM to be active.
# When supported, the cold migration may be used as a fallback
# migration mechanism to move non active VMs.
LOG.error(
'Cannot live migrate: instance_uuid=%(instance_uuid)s, '
'state=%(instance_state)s.', dict(
instance_uuid=instance.uuid,
instance_state=instance_state_str))
return
migration_type = 'live'
# Here will makes repeated actions to enable the same compute node,
# when migrating VMs to the destination node which is disabled.
# Whether should we remove the same actions in the solution???
destination_node_status_str = self.get_node_status_str(
destination_node)
if destination_node_status_str == element.ServiceState.DISABLED.value:
self.add_action_enable_compute_node(destination_node)
if self.compute_model.migrate_instance(
instance, source_node, destination_node):
params = {'migration_type': migration_type,
'source_node': source_node.uuid,
'destination_node': destination_node.uuid}
self.solution.add_action(action_type=self.MIGRATION,
resource_id=instance.uuid,
input_parameters=params)
self.number_of_migrations += 1
def disable_unused_nodes(self):
"""Generate actions for disabling unused nodes.
:return: None
"""
for node in self.get_available_compute_nodes().values():
if (len(self.compute_model.get_node_instances(node)) == 0 and
node.status !=
element.ServiceState.DISABLED.value):
self.add_action_disable_node(node)
def get_instance_utilization(self, instance):
"""Collect cpu, ram and disk utilization statistics of a VM.
:param instance: instance object
:param aggr: string
:return: dict(cpu(number of vcpus used), ram(MB used), disk(B used))
"""
instance_cpu_util = None
instance_ram_util = None
instance_disk_util = None
if instance.uuid in self.datasource_instance_data_cache.keys():
return self.datasource_instance_data_cache.get(instance.uuid)
instance_cpu_util = self.datasource_backend.get_instance_cpu_usage(
instance.uuid,
self.period,
self.AGGREGATION,
granularity=self.granularity)
instance_ram_util = self.datasource_backend.get_instance_memory_usage(
instance.uuid,
self.period,
self.AGGREGATION,
granularity=self.granularity)
if not instance_ram_util:
instance_ram_util = (
self.datasource_backend.get_instance_ram_allocated(
instance.uuid,
self.period,
self.AGGREGATION,
granularity=self.granularity))
instance_disk_util = (
self.datasource_backend.get_instance_root_disk_allocated(
instance.uuid,
self.period,
self.AGGREGATION,
granularity=self.granularity))
if instance_cpu_util:
total_cpu_utilization = (
instance.vcpus * (instance_cpu_util / 100.0))
else:
total_cpu_utilization = instance.vcpus
if not instance_ram_util:
instance_ram_util = instance.memory
LOG.warning('No values returned by %s for memory.resident, '
'use instance flavor ram value', instance.uuid)
if not instance_disk_util:
instance_disk_util = instance.disk
LOG.warning('No values returned by %s for disk.root.size, '
'use instance flavor disk value', instance.uuid)
self.datasource_instance_data_cache[instance.uuid] = dict(
cpu=total_cpu_utilization, ram=instance_ram_util,
disk=instance_disk_util)
return self.datasource_instance_data_cache.get(instance.uuid)
def get_node_utilization(self, node):
"""Collect cpu, ram and disk utilization statistics of a node.
:param node: node object
:param aggr: string
:return: dict(cpu(number of cores used), ram(MB used), disk(B used))
"""
node_instances = self.compute_model.get_node_instances(node)
node_ram_util = 0
node_disk_util = 0
node_cpu_util = 0
for instance in node_instances:
instance_util = self.get_instance_utilization(
instance)
node_cpu_util += instance_util['cpu']
node_ram_util += instance_util['ram']
node_disk_util += instance_util['disk']
return dict(cpu=node_cpu_util, ram=node_ram_util,
disk=node_disk_util)
def get_node_capacity(self, node):
"""Collect cpu, ram and disk capacity of a node.
:param node: node object
:return: dict(cpu(cores), ram(MB), disk(B))
"""
return dict(cpu=node.vcpus, ram=node.memory, disk=node.disk_capacity)
def get_relative_node_utilization(self, node):
"""Return relative node utilization.
:param node: node object
:return: {'cpu': <0,1>, 'ram': <0,1>, 'disk': <0,1>}
"""
relative_node_utilization = {}
util = self.get_node_utilization(node)
cap = self.get_node_capacity(node)
for k in util.keys():
relative_node_utilization[k] = float(util[k]) / float(cap[k])
return relative_node_utilization
def get_relative_cluster_utilization(self):
"""Calculate relative cluster utilization (rcu).
RCU is an average of relative utilizations (rhu) of active nodes.
:return: {'cpu': <0,1>, 'ram': <0,1>, 'disk': <0,1>}
"""
nodes = self.get_available_compute_nodes().values()
rcu = {}
counters = {}
for node in nodes:
node_status_str = self.get_node_status_str(node)
if node_status_str == element.ServiceState.ENABLED.value:
rhu = self.get_relative_node_utilization(node)
for k in rhu.keys():
if k not in rcu:
rcu[k] = 0
if k not in counters:
counters[k] = 0
rcu[k] += rhu[k]
counters[k] += 1
for k in rcu.keys():
rcu[k] /= counters[k]
return rcu
def is_overloaded(self, node, cc):
"""Indicate whether a node is overloaded.
This considers provided resource capacity coefficients (cc).
:param node: node object
:param cc: dictionary containing resource capacity coefficients
:return: [True, False]
"""
node_capacity = self.get_node_capacity(node)
node_utilization = self.get_node_utilization(
node)
metrics = ['cpu']
for m in metrics:
if node_utilization[m] > node_capacity[m] * cc[m]:
return True
return False
def instance_fits(self, instance, node, cc):
"""Indicate whether is a node able to accommodate a VM.
This considers provided resource capacity coefficients (cc).
:param instance: :py:class:`~.element.Instance`
:param node: node object
:param cc: dictionary containing resource capacity coefficients
:return: [True, False]
"""
node_capacity = self.get_node_capacity(node)
node_utilization = self.get_node_utilization(node)
instance_utilization = self.get_instance_utilization(instance)
metrics = ['cpu', 'ram', 'disk']
for m in metrics:
if (instance_utilization[m] + node_utilization[m] >
node_capacity[m] * cc[m]):
return False
return True
def optimize_solution(self):
"""Optimize solution.
This is done by eliminating unnecessary or circular set of migrations
which can be replaced by a more efficient solution.
e.g.:
* A->B, B->C => replace migrations A->B, B->C with
a single migration A->C as both solution result in
VM running on node C which can be achieved with
one migration instead of two.
* A->B, B->A => remove A->B and B->A as they do not result
in a new VM placement.
"""
migrate_actions = (
a for a in self.solution.actions if a[
'action_type'] == self.MIGRATION)
instance_to_be_migrated = (
a['input_parameters']['resource_id'] for a in migrate_actions)
instance_uuids = list(set(instance_to_be_migrated))
for instance_uuid in instance_uuids:
actions = list(
a for a in self.solution.actions if a[
'input_parameters'][
'resource_id'] == instance_uuid)
if len(actions) > 1:
src_uuid = actions[0]['input_parameters']['source_node']
dst_uuid = actions[-1]['input_parameters']['destination_node']
for a in actions:
self.solution.actions.remove(a)
self.number_of_migrations -= 1
src_node = self.compute_model.get_node_by_uuid(src_uuid)
dst_node = self.compute_model.get_node_by_uuid(dst_uuid)
instance = self.compute_model.get_instance_by_uuid(
instance_uuid)
if self.compute_model.migrate_instance(
instance, dst_node, src_node):
self.add_migration(instance, src_node, dst_node)
def offload_phase(self, cc):
"""Perform offloading phase.
This considers provided resource capacity coefficients.
Offload phase performing first-fit based bin packing to offload
overloaded nodes. This is done in a fashion of moving
the least CPU utilized VM first as live migration these
generally causes less troubles. This phase results in a cluster
with no overloaded nodes.
* This phase is be able to enable disabled nodes (if needed
and any available) in the case of the resource capacity provided by
active nodes is not able to accommodate all the load.
As the offload phase is later followed by the consolidation phase,
the node enabler in this phase doesn't necessarily results
in more enabled nodes in the final solution.
:param cc: dictionary containing resource capacity coefficients
"""
sorted_nodes = sorted(
self.get_available_compute_nodes().values(),
key=lambda x: self.get_node_utilization(x)['cpu'])
for node in reversed(sorted_nodes):
if self.is_overloaded(node, cc):
for instance in sorted(
self.compute_model.get_node_instances(node),
key=lambda x: self.get_instance_utilization(
x)['cpu']
):
# skip exclude instance when migrating
if instance.watcher_exclude:
LOG.debug("Instance is excluded by scope, "
"skipped: %s", instance.uuid)
continue
for destination_node in reversed(sorted_nodes):
if self.instance_fits(
instance, destination_node, cc):
self.add_migration(instance, node,
destination_node)
break
if not self.is_overloaded(node, cc):
break
def consolidation_phase(self, cc):
"""Perform consolidation phase.
This considers provided resource capacity coefficients.
Consolidation phase performing first-fit based bin packing.
First, nodes with the lowest cpu utilization are consolidated
by moving their load to nodes with the highest cpu utilization
which can accommodate the load. In this phase the most cpu utilized
VMs are prioritized as their load is more difficult to accommodate
in the system than less cpu utilized VMs which can be later used
to fill smaller CPU capacity gaps.
:param cc: dictionary containing resource capacity coefficients
"""
sorted_nodes = sorted(
self.get_available_compute_nodes().values(),
key=lambda x: self.get_node_utilization(x)['cpu'])
asc = 0
for node in sorted_nodes:
instances = sorted(
self.compute_model.get_node_instances(node),
key=lambda x: self.get_instance_utilization(x)['cpu'])
for instance in reversed(instances):
# skip exclude instance when migrating
if instance.watcher_exclude:
LOG.debug("Instance is excluded by scope, "
"skipped: %s", instance.uuid)
continue
dsc = len(sorted_nodes) - 1
for destination_node in reversed(sorted_nodes):
if asc >= dsc:
break
if self.instance_fits(
instance, destination_node, cc):
self.add_migration(instance, node,
destination_node)
break
dsc -= 1
asc += 1
def pre_execute(self):
self._pre_execute()
def do_execute(self):
"""Execute strategy.
This strategy produces a solution resulting in more
efficient utilization of cluster resources using following
four phases:
* Offload phase - handling over-utilized resources
* Consolidation phase - handling under-utilized resources
* Solution optimization - reducing number of migrations
* Disability of unused nodes
:param original_model: root_model object
"""
LOG.info('Executing Smart Strategy')
rcu = self.get_relative_cluster_utilization()
cc = {'cpu': 1.0, 'ram': 1.0, 'disk': 1.0}
# Offloading phase
self.offload_phase(cc)
# Consolidation phase
self.consolidation_phase(cc)
# Optimize solution
self.optimize_solution()
# disable unused nodes
self.disable_unused_nodes()
rcu_after = self.get_relative_cluster_utilization()
info = {
"compute_nodes_count": len(
self.get_available_compute_nodes()),
'number_of_migrations': self.number_of_migrations,
'number_of_released_nodes':
self.number_of_released_nodes,
'relative_cluster_utilization_before': str(rcu),
'relative_cluster_utilization_after': str(rcu_after)
}
LOG.debug(info)
def post_execute(self):
self.solution.set_efficacy_indicators(
compute_nodes_count=len(
self.get_available_compute_nodes()),
released_compute_nodes_count=self.number_of_released_nodes,
instance_migrations_count=self.number_of_migrations,
)
LOG.debug(self.compute_model.to_string())
Reference in New Issue View Git Blame Copy Permalink