1 files changed, 41 insertions, 0 deletions
diff --git a/nova/scheduler/weights/cpu.py b/nova/scheduler/weights/cpu.py
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+++ b/nova/scheduler/weights/cpu.py
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+# Copyright (c) 2016, Red Hat Inc.
+# 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.
+
+"""
+CPU Weigher.  Weigh hosts by their CPU usage.
+
+The default is to spread instances across all hosts evenly.  If you prefer
+stacking, you can set the 'cpu_weight_multiplier' option to a negative
+number and the weighing has the opposite effect of the default.
+"""
+
+import nova.conf
+from nova.scheduler import weights
+
+CONF = nova.conf.CONF
+
+
+class CPUWeigher(weights.BaseHostWeigher):
+    minval = 0
+
+    def weight_multiplier(self):
+        """Override the weight multiplier."""
+        return CONF.filter_scheduler.cpu_weight_multiplier
+
+    def _weigh_object(self, host_state, weight_properties):
+        """Higher weights win.  We want spreading to be the default."""
+        vcpus_free = (host_state.vcpus_total * host_state.cpu_allocation_ratio
+                      - host_state.vcpus_used)
+        return vcpus_free