60 lines
2.2 KiB
Python
60 lines
2.2 KiB
Python
# Copyright (c) 2014 Cisco Systems Inc.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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from oslo.config import cfg
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from nova.openstack.common.gettextutils import _
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from nova.openstack.common import log as logging
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from nova.scheduler.solvers import constraints
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LOG = logging.getLogger(__name__)
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CONF = cfg.CONF
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CONF.import_opt('max_io_ops_per_host', 'nova.scheduler.filters.io_ops_filter')
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class IoOpsConstraint(constraints.BaseLinearConstraint):
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"""A constraint to ensure only those hosts are selected whose number of
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concurrent I/O operations are within a set threshold.
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"""
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def get_constraint_matrix(self, hosts, filter_properties):
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max_io_ops = CONF.max_io_ops_per_host
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num_hosts = len(hosts)
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num_instances = filter_properties.get('num_instances')
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constraint_matrix = [[True for j in xrange(num_instances)]
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for i in xrange(num_hosts)]
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for i in xrange(num_hosts):
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num_io_ops = hosts[i].num_io_ops
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acceptable_num_instances = int(max_io_ops - num_io_ops)
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if acceptable_num_instances < 0:
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acceptable_num_instances = 0
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if acceptable_num_instances < num_instances:
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inacceptable_num = (num_instances - acceptable_num_instances)
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constraint_matrix[i] = (
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[True for j in xrange(acceptable_num_instances)] +
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[False for j in xrange(inacceptable_num)])
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LOG.debug(_("%(host)s can accept %(num)s requested instances "
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"according to IoOpsConstraint."),
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{'host': hosts[i],
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'num': acceptable_num_instances})
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return constraint_matrix
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