old_contents: # 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.openstack.common import cfg
  from nova.openstack.common import log as logging
  from nova.scheduler import filters
  
  LOG = logging.getLogger(__name__)
  
  ram_allocation_ratio_opt = cfg.FloatOpt("ram_allocation_ratio",
          default=1.5,
          help="virtual ram to physical ram allocation ratio")
  
  FLAGS = flags.FLAGS
  FLAGS.register_opt(ram_allocation_ratio_opt)
  
  
  class RamFilter(filters.BaseHostFilter):
      """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
          total_usable_ram_mb = host_state.total_usable_ram_mb
          used_ram_mb = total_usable_ram_mb - free_ram_mb
          return (total_usable_ram_mb * FLAGS.ram_allocation_ratio -
                  used_ram_mb >= requested_ram)
  
new_contents: # 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.openstack.common import cfg
  from nova.openstack.common import log as logging
  from nova.scheduler import filters
  
  LOG = logging.getLogger(__name__)
  
  ram_allocation_ratio_opt = cfg.FloatOpt("ram_allocation_ratio",
          default=1.5,
          help="virtual ram to physical ram allocation ratio")
  
  FLAGS = flags.FLAGS
  FLAGS.register_opt(ram_allocation_ratio_opt)
  
  
  class RamFilter(filters.BaseHostFilter):
      """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
          total_usable_ram_mb = host_state.total_usable_ram_mb
          used_ram_mb = total_usable_ram_mb - free_ram_mb
          usable_ram = (total_usable_ram_mb * FLAGS.ram_allocation_ratio -
                  used_ram_mb)
          if not usable_ram >= requested_ram:
              LOG.debug(_("%(host_state)s does not have %(requested_ram)s MB "
                      "usable ram, it only has %(usable_ram)s MB usable ram."),
                      locals())
              return False
          return True
  
subject: Add debug output to RamFilter