OpenStack Study: core_filter.py

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# 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 nova import db

from nova.openstack.common.gettextutils import _

from nova.openstack.common import log as logging

from nova.scheduler import filters

LOG = logging.getLogger(__name__)

cpu_allocation_ratio_opt = cfg.FloatOpt('cpu_allocation_ratio',

default=16.0,

help='Virtual CPU to physical CPU allocation ratio which affects '

'all CPU filters. This configuration specifies a global ratio '

'for CoreFilter. For AggregateCoreFilter, it will fall back to '

'this configuration value if no per-aggregate setting found.')

CONF = cfg.CONF

CONF.register_opt(cpu_allocation_ratio_opt)

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class BaseCoreFilter(filters.BaseHostFilter):

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def _get_cpu_allocation_ratio(self, host_state, filter_properties):

raise NotImplementedError

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def host_passes(self, host_state, filter_properties):

"""Return True if host has sufficient CPU cores."""

instance_type = filter_properties.get('instance_type')

if not instance_type:

return True

if not host_state.vcpus_total:

# Fail safe

LOG.warning(_("VCPUs not set; assuming CPU collection broken"))

return True

instance_vcpus = instance_type['vcpus']

cpu_allocation_ratio = self._get_cpu_allocation_ratio(host_state,

filter_properties)

vcpus_total = host_state.vcpus_total * cpu_allocation_ratio

# Only provide a VCPU limit to compute if the virt driver is reporting

# an accurate count of installed VCPUs. (XenServer driver does not)

if vcpus_total > 0:

host_state.limits['vcpu'] = vcpus_total

return (vcpus_total - host_state.vcpus_used) >= instance_vcpus

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class CoreFilter(BaseCoreFilter):

"""CoreFilter filters based on CPU core utilization."""

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def _get_cpu_allocation_ratio(self, host_state, filter_properties):

return CONF.cpu_allocation_ratio

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class AggregateCoreFilter(BaseCoreFilter):

"""AggregateCoreFilter with per-aggregate CPU subscription flag.

Fall back to global cpu_allocation_ratio if no per-aggregate setting found.

"""

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def _get_cpu_allocation_ratio(self, host_state, filter_properties):

context = filter_properties['context'].elevated()

# TODO(uni): DB query in filter is a performance hit, especially for

# system with lots of hosts. Will need a general solution here to fix

# all filters with aggregate DB call things.

metadata = db.aggregate_metadata_get_by_host(

context, host_state.host, key='cpu_allocation_ratio')

aggregate_vals = metadata.get('cpu_allocation_ratio', set())

num_values = len(aggregate_vals)

if num_values == 0:

return CONF.cpu_allocation_ratio

if num_values > 1:

LOG.warning(_("%(num_values)d ratio values found, "

"of which the minimum value will be used."),

{'num_values': num_values})

try:

ratio = float(min(aggregate_vals))

except ValueError as e:

LOG.warning(_("Could not decode cpu_allocation_ratio: '%s'"), e)

ratio = CONF.cpu_allocation_ratio

return ratio