Merge "update default overcommit"

Author: Zuul

doc/source/admin/scheduling.rst

@@ -1100,6 +1100,16 @@ control the initial allocation ratio values for a compute node:
 * :oslo.config:option:`initial_disk_allocation_ratio` the initial DISK_GB
   inventory allocation ratio for a new compute node record, defaults to 1.0
 
+Starting with the 27.0.0 Antelope release, the following default values are used
+for the initial allocation ratio values for a compute node:
+
+* :oslo.config:option:`initial_cpu_allocation_ratio` the initial VCPU
+  inventory allocation ratio for a new compute node record, defaults to 4.0
+* :oslo.config:option:`initial_ram_allocation_ratio` the initial MEMORY_MB
+  inventory allocation ratio for a new compute node record, defaults to 1.0
+* :oslo.config:option:`initial_disk_allocation_ratio` the initial DISK_GB
+  inventory allocation ratio for a new compute node record, defaults to 1.0
+
 Scheduling considerations
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 

nova/conf/compute.py

@@ -529,7 +529,7 @@
 * ``initial_disk_allocation_ratio``
 """),
     cfg.FloatOpt('initial_cpu_allocation_ratio',
-                 default=16.0,
+                 default=4.0,
                  min=0.0,
                  help="""
 Initial virtual CPU to physical CPU allocation ratio.
@@ -545,7 +545,7 @@
 * ``cpu_allocation_ratio``
 """),
     cfg.FloatOpt('initial_ram_allocation_ratio',
-                 default=1.5,
+                 default=1.0,
                  min=0.0,
                  help="""
 Initial virtual RAM to physical RAM allocation ratio.

nova/tests/functional/test_server_group.py

@@ -103,7 +103,10 @@ class ServerGroupFakeDriver(fake.SmallFakeDriver):
     """
 
     vcpus = 1000
-    memory_mb = 8192
+    # the testcases were built with a default ram allocation ratio
+    # of 1.5 and 8192 mb of ram so to maintain the same capacity with
+    # the new default allocation ratio of 1.0 we use 8192+4096=12288
+    memory_mb = 12288
     local_gb = 100000
 
 

nova/tests/functional/test_servers_provider_tree.py

@@ -82,15 +82,15 @@ def setUp(self):
             },
             'MEMORY_MB': {
                 'total': 8192,
-                'allocation_ratio': 1.5,
+                'allocation_ratio': 1.0,
                 'max_unit': 8192,
                 'min_unit': 1,
                 'reserved': 512,
                 'step_size': 1,
             },
             'VCPU': {
                 'total': 10,
-                'allocation_ratio': 16.0,
+                'allocation_ratio': 4.0,
                 'max_unit': 10,
                 'min_unit': 1,
                 'reserved': 0,

nova/tests/unit/objects/test_compute_node.py

@@ -666,8 +666,8 @@ def test_compat_allocation_ratios_zero_conf(self, mock_update):
             CONF.initial_disk_allocation_ratio, compute.disk_allocation_ratio)
 
         mock_update.assert_called_once_with(
-            self.context, 123, {'cpu_allocation_ratio': 16.0,
-                                'ram_allocation_ratio': 1.5,
+            self.context, 123, {'cpu_allocation_ratio': 4.0,
+                                'ram_allocation_ratio': 1.0,
                                 'disk_allocation_ratio': 1.0})
 
     @mock.patch('nova.db.main.api.compute_node_update')
@@ -694,8 +694,8 @@ def test_compat_allocation_ratios_None_conf_zero_values(self, mock_update):
             CONF.initial_disk_allocation_ratio, compute.disk_allocation_ratio)
 
         mock_update.assert_called_once_with(
-            self.context, 123, {'cpu_allocation_ratio': 16.0,
-                                'ram_allocation_ratio': 1.5,
+            self.context, 123, {'cpu_allocation_ratio': 4.0,
+                                'ram_allocation_ratio': 1.0,
                                 'disk_allocation_ratio': 1.0})
 
     @mock.patch('nova.db.main.api.compute_node_update')
@@ -722,8 +722,8 @@ def test_compat_allocation_ratios_None_conf_None_values(self, mock_update):
             CONF.initial_disk_allocation_ratio, compute.disk_allocation_ratio)
 
         mock_update.assert_called_once_with(
-            self.context, 123, {'cpu_allocation_ratio': 16.0,
-                                'ram_allocation_ratio': 1.5,
+            self.context, 123, {'cpu_allocation_ratio': 4.0,
+                                'ram_allocation_ratio': 1.0,
                                 'disk_allocation_ratio': 1.0})
 
     def test_get_all_by_not_mapped(self):

nova/tests/unit/virt/libvirt/test_driver.py

@@ -21366,7 +21366,7 @@ def _get_inventory(self):
                 'min_unit': 1,
                 'max_unit': self.vcpus,
                 'step_size': 1,
-                'allocation_ratio': 16.0,
+                'allocation_ratio': 4.0,
                 'reserved': 0,
             },
             orc.PCPU: {
@@ -21382,7 +21382,7 @@ def _get_inventory(self):
                 'min_unit': 1,
                 'max_unit': self.memory_mb,
                 'step_size': 1,
-                'allocation_ratio': 1.5,
+                'allocation_ratio': 1.0,
                 'reserved': 512,
             },
             orc.DISK_GB: {

nova/tests/unit/virt/vmwareapi/test_driver_api.py

@@ -2123,15 +2123,15 @@ def test_update_provider_tree(self, mock_get_avail_ds):
                 'min_unit': 1,
                 'max_unit': 16,
                 'step_size': 1,
-                'allocation_ratio': 16.0,
+                'allocation_ratio': 4.0,
             },
             orc.MEMORY_MB: {
                 'total': 2048,
                 'reserved': 512,
                 'min_unit': 1,
                 'max_unit': 1024,
                 'step_size': 1,
-                'allocation_ratio': 1.5,
+                'allocation_ratio': 1.0,
             },
             orc.DISK_GB: {
                 'total': 95,

releasenotes/notes/update-initial-allocation-defaults-94106033b66b8fa0.yaml

@@ -0,0 +1,21 @@
+---
+upgrade:
+  - |
+    In this release the default values for the initial ram and cpu allocation
+    ratios have been updated to 1.0 and 4.0 respectively. This will not
+    affect any existing compute node resource providers but the new default
+    will take effect on the creation of new resource providers.
+other:
+  - |
+    The default initial allocation ratios enabled ram over commit by default
+    with a factor of ``1.5``. This value was chosen early in nova's history
+    as the predominant workload was web hosting or other light weight
+    virtualization. Similarly the default initial cpu allocation ratio
+    defaulted to 16. As more demanding workload from telco, enterprise,
+    scientific and governmental users became the norm the initial values we
+    had chosen became less and less correct overtime. These have now been
+    updated to reflect a more reasonable default for the majority of our users.
+    As of this release the initial ram allocation value is 1.0 disabling
+    overcommit by default for new compute nodes and the initial cpu allocation
+    ratio is now 4.0 which is a more reasonable overcommit for non idle
+    workloads.