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Viewing changes to nova/tests/scheduler/test_least_cost_scheduler.py

  • Committer: Monsyne Dragon
  • Date: 2011-06-28 10:23:00 UTC
  • mfrom: (1077.1.141 nova)
  • Revision ID: mdragon@rackspace.com-20110628102300-lnkdr13k8uuyp30i
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nova/tests/scheduler/test_least_cost_scheduler.py
 
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# Copyright 2011 OpenStack LLC.
 
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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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"""
 
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Tests For Least Cost Scheduler
 
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"""
 
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from nova import flags
 
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from nova import test
 
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from nova.scheduler import least_cost
 
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from nova.tests.scheduler import test_zone_aware_scheduler
 
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MB = 1024 * 1024
 
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FLAGS = flags.FLAGS
 
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class FakeHost(object):
 
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    def __init__(self, host_id, free_ram, io):
 
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        self.id = host_id
 
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        self.free_ram = free_ram
 
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        self.io = io
 
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class WeightedSumTestCase(test.TestCase):
 
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    def test_empty_domain(self):
 
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        domain = []
 
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        weighted_fns = []
 
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        result = least_cost.weighted_sum(domain, weighted_fns)
 
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        expected = []
 
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        self.assertEqual(expected, result)
 
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    def test_basic_costing(self):
 
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        hosts = [
 
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            FakeHost(1, 512 * MB, 100),
 
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            FakeHost(2, 256 * MB, 400),
 
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            FakeHost(3, 512 * MB, 100),
 
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        ]
 
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        weighted_fns = [
 
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            (1, lambda h: h.free_ram),  # Fill-first, free_ram is a *cost*
 
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            (2, lambda h: h.io),  # Avoid high I/O
 
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        ]
 
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        costs = least_cost.weighted_sum(
 
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            domain=hosts, weighted_fns=weighted_fns)
 
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        # Each 256 MB unit of free-ram contributes 0.5 points by way of:
 
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        #   cost = weight * (score/max_score) = 1 * (256/512) = 0.5
 
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        # Each 100 iops of IO adds 0.5 points by way of:
 
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        #   cost = 2 * (100/400) = 2 * 0.25 = 0.5
 
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        expected = [1.5, 2.5, 1.5]
 
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        self.assertEqual(expected, costs)
 
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class LeastCostSchedulerTestCase(test.TestCase):
 
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    def setUp(self):
 
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        super(LeastCostSchedulerTestCase, self).setUp()
 
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        class FakeZoneManager:
 
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            pass
 
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        zone_manager = FakeZoneManager()
 
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        states = test_zone_aware_scheduler.fake_zone_manager_service_states(
 
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            num_hosts=10)
 
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        zone_manager.service_states = states
 
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        self.sched = least_cost.LeastCostScheduler()
 
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        self.sched.zone_manager = zone_manager
 
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    def tearDown(self):
 
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        super(LeastCostSchedulerTestCase, self).tearDown()
 
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    def assertWeights(self, expected, num, request_spec, hosts):
 
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        weighted = self.sched.weigh_hosts(num, request_spec, hosts)
 
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        self.assertDictListMatch(weighted, expected, approx_equal=True)
 
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    def test_no_hosts(self):
 
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        num = 1
 
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        request_spec = {}
 
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        hosts = []
 
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        expected = []
 
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        self.assertWeights(expected, num, request_spec, hosts)
 
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    def test_noop_cost_fn(self):
 
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        FLAGS.least_cost_scheduler_cost_functions = [
 
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            'nova.scheduler.least_cost.noop_cost_fn',
 
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        ]
 
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        FLAGS.noop_cost_fn_weight = 1
 
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        num = 1
 
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        request_spec = {}
 
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        hosts = self.sched.filter_hosts(num, request_spec)
 
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        expected = [dict(weight=1, hostname=hostname)
 
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                    for hostname, caps in hosts]
 
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        self.assertWeights(expected, num, request_spec, hosts)
 
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    def test_cost_fn_weights(self):
 
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        FLAGS.least_cost_scheduler_cost_functions = [
 
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            'nova.scheduler.least_cost.noop_cost_fn',
 
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        ]
 
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        FLAGS.noop_cost_fn_weight = 2
 
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        num = 1
 
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        request_spec = {}
 
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        hosts = self.sched.filter_hosts(num, request_spec)
 
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        expected = [dict(weight=2, hostname=hostname)
 
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                    for hostname, caps in hosts]
 
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        self.assertWeights(expected, num, request_spec, hosts)
 
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    def test_fill_first_cost_fn(self):
 
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        FLAGS.least_cost_scheduler_cost_functions = [
 
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            'nova.scheduler.least_cost.fill_first_cost_fn',
 
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        ]
 
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        FLAGS.fill_first_cost_fn_weight = 1
 
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        num = 1
 
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        request_spec = {}
 
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        hosts = self.sched.filter_hosts(num, request_spec)
 
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        expected = []
 
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        for idx, (hostname, caps) in enumerate(hosts):
 
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            # Costs are normalized so over 10 hosts, each host with increasing
 
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            # free ram will cost 1/N more. Since the lowest cost host has some
 
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            # free ram, we add in the 1/N for the base_cost
 
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            weight = 0.1 + (0.1 * idx)
 
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            weight_dict = dict(weight=weight, hostname=hostname)
 
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            expected.append(weight_dict)
 
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        self.assertWeights(expected, num, request_spec, hosts)