92 lines
2.8 KiB
Python
92 lines
2.8 KiB
Python
# Copyright 2012 Anton Beloglazov
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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""" OTF threshold based algorithms.
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"""
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from contracts import contract
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from neat.contracts_extra import *
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import logging
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log = logging.getLogger(__name__)
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@contract
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def otf_factory(time_step, migration_time, params):
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""" Creates the OTF algorithm with limiting and migration time.
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:param time_step: The length of the simulation time step in seconds.
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:type time_step: int,>=0
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:param migration_time: The VM migration time in time seconds.
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:type migration_time: float,>=0
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:param params: A dictionary containing the algorithm's parameters.
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:type params: dict(str: *)
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:return: A function implementing the OTF algorithm.
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:rtype: function
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"""
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migration_time_normalized = float(migration_time) / time_step
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def otf_wrapper(utilization, state=None):
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if state is None or state == {}:
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state = {'overload': 0,
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'total': 0}
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return otf(params['otf'],
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params['threshold'],
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params['limit'],
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migration_time_normalized,
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utilization,
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state)
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return otf_wrapper
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@contract
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def otf(otf, threshold, limit, migration_time, utilization, state):
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""" The OTF threshold algorithm with limiting and migration time.
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:param otf: The threshold on the OTF value.
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:type otf: float,>=0
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:param threshold: The utilization overload threshold.
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:type threshold: float,>=0
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:param limit: The minimum number of values in the utilization history.
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:type limit: int,>=0
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:param migration_time: The VM migration time in time steps.
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:type migration_time: float,>=0
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:param utilization: The history of the host's CPU utilization.
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:type utilization: list(float)
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:param state: The state dictionary.
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:type state: dict(str: *)
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:return: The decision of the algorithm and updated state.
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:rtype: tuple(bool, dict(*: *))
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"""
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state['total'] += 1
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if utilization[-1] >= threshold:
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state['overload'] += 1
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if len(utilization) < limit:
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decision = False
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else:
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decision = (migration_time + state['overload']) / \
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(migration_time + state['total']) >= otf
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return (decision, state)
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