Pull out ram_filter into a separate filter

Change-Id: Id38bbd0e8dbcd00fee836d555005b954973ae90c

nova/scheduler/filters/__init__.py

@@ -34,3 +34,4 @@ from abstract_filter import AbstractHostFilter
 from all_hosts_filter import AllHostsFilter
 from compute_filter import ComputeFilter
 from json_filter import JsonFilter
+from ram_filter import RamFilter

nova/scheduler/filters/compute_filter.py

@@ -38,12 +38,6 @@ class ComputeFilter(abstract_filter.AbstractHostFilter):
                 return False
         return True
 
-    def _basic_ram_filter(self, host_state, instance_type):
-        """Only return hosts with sufficient available RAM."""
-        requested_ram = instance_type['memory_mb']
-        free_ram_mb = host_state.free_ram_mb
-        return free_ram_mb >= requested_ram
-
     def host_passes(self, host_state, filter_properties):
         """Return a list of hosts that can create instance_type."""
         instance_type = filter_properties.get('instance_type')
@@ -54,8 +48,6 @@ class ComputeFilter(abstract_filter.AbstractHostFilter):
 
         if not utils.service_is_up(service) or service['disabled']:
             return False
-        if not self._basic_ram_filter(host_state, instance_type):
-            return False
         if not capabilities.get("enabled", True):
             return False
         if not self._satisfies_extra_specs(capabilities, instance_type):

nova/scheduler/filters/ram_filter.py

@@ -0,0 +1,36 @@
+# Copyright (c) 2011 Openstack, LLC.
+# Copyright (c) 2012 Cloudscaling
+# All Rights Reserved.
+#
+#    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 nova import flags
+from nova import log as logging
+from nova.scheduler.filters import abstract_filter
+
+LOG = logging.getLogger('nova.scheduler.filter.ram_filter')
+
+FLAGS = flags.FLAGS
+flags.DEFINE_float("ram_allocation_ratio", 1.0,
+                     "virtual ram to physical ram allocation ratio")
+
+
+class RamFilter(abstract_filter.AbstractHostFilter):
+    """Ram Filter with over subscription flag"""
+
+    def host_passes(self, host_state, filter_properties):
+        """Only return hosts with sufficient available RAM."""
+        instance_type = filter_properties.get('instance_type')
+        requested_ram = instance_type['memory_mb']
+        free_ram_mb = host_state.free_ram_mb
+        return free_ram_mb * FLAGS.ram_allocation_ratio >= requested_ram

nova/scheduler/host_manager.py

@@ -32,7 +32,7 @@ flags.DEFINE_integer('reserved_host_disk_mb', 0,
         'Amount of disk in MB to reserve for host/dom0')
 flags.DEFINE_integer('reserved_host_memory_mb', 512,
         'Amount of memory in MB to reserve for host/dom0')
-flags.DEFINE_list('default_host_filters', ['ComputeFilter'],
+flags.DEFINE_list('default_host_filters', ['RamFilter', 'ComputeFilter'],
         'Which filters to use for filtering hosts when not specified '
         'in the request.')
 

nova/tests/scheduler/test_host_filters.py

@@ -53,9 +53,9 @@ class HostFiltersTestCase(test.TestCase):
                  'service': service})
         self.assertTrue(filt_cls.host_passes(host, filter_properties))
 
-    def test_compute_filter_fails_on_memory(self):
+    def test_ram_filter_fails_on_memory(self):
         self._stub_service_is_up(True)
-        filt_cls = filters.ComputeFilter()
+        filt_cls = filters.RamFilter()
         filter_properties = {'instance_type': {'memory_mb': 1024}}
         capabilities = {'enabled': True}
         service = {'disabled': False}