Allow the cpu_shared_set to be configurable

This patch allows puppet-nova to set [compute]/cpu_shared_set.

Fixes bug 1776905

Change-Id: I5b15258e3bf6192b0bff71fb080a1db323456a66

manifests/compute.pp

@@ -114,6 +114,12 @@
 #   for virtual machine processes
 #   Defaults to $::os_service_default
 #
+#  [*cpu_shared_set*]
+#   (optional) A list or range of physical CPU cores to reserve
+#   for for best-effort guest vCPU resources (e.g. emulator threads in
+#   libvirt/QEMU)
+#   Defaults to $::os_service_default
+#
 #  [*resume_guests_state_on_host_boot*]
 #   (optional) This option specifies whether to start guests that were running before the
 #   host rebooted. It ensures that all of the instances on a Nova compute node
@@ -189,6 +195,7 @@ class nova::compute (
   $allow_resize_to_same_host                   = false,
   $resize_confirm_window                       = $::os_service_default,
   $vcpu_pin_set                                = $::os_service_default,
+  $cpu_shared_set                              = $::os_service_default,
   $resume_guests_state_on_host_boot            = $::os_service_default,
   $barbican_auth_endpoint                      = $::os_service_default,
   $barbican_endpoint                           = $::os_service_default,
@@ -206,6 +213,7 @@ class nova::compute (
   include ::nova::params
 
   $vcpu_pin_set_real = pick(join(any2array($vcpu_pin_set), ','), $::os_service_default)
+  $cpu_shared_set_real = pick(join(any2array($cpu_shared_set), ','), $::os_service_default)
 
   include ::nova::pci
 
@@ -247,6 +255,7 @@ class nova::compute (
     'DEFAULT/resize_confirm_window':             value => $resize_confirm_window;
     'DEFAULT/vcpu_pin_set':                      value => $vcpu_pin_set_real;
     'DEFAULT/resume_guests_state_on_host_boot':  value => $resume_guests_state_on_host_boot;
+    'compute/cpu_shared_set':                    value => $cpu_shared_set_real;
     'key_manager/backend':                       value => $keymgr_backend_real;
     'barbican/auth_endpoint':                    value => $barbican_auth_endpoint;
     'barbican/barbican_endpoint':                value => $barbican_endpoint;

releasenotes/notes/compute-cpu-shared-set-30e2394d1af2dd47.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    Add support for configuring cpu_shared_set
+
+    Some workloads run best when the hypervisor overhead processes (emulator threads in libvirt/QEMU) can be placed on different physical host CPUs than other guest CPU resources. This allow
+    those workloads to prevent latency spikes for guest vCPU threads. 
+
+    To place a workload's emulator threads on a set of isolated physical CPUs, set the configuration option to the set of host CPUs that should be used for best-effort CPU resources. Then set
+    a flavor extra spec to ``hw:emulator_threads_policy=share`` to instruct nova to place that workload's emulator threads on that set of host CPUs.

spec/classes/nova_compute_spec.rb

@@ -28,6 +28,7 @@ describe 'nova::compute' do
       it { is_expected.to contain_nova_config('DEFAULT/resize_confirm_window').with_value('<SERVICE DEFAULT>') }
       it { is_expected.to contain_nova_config('DEFAULT/vcpu_pin_set').with(:value => '<SERVICE DEFAULT>') }
       it { is_expected.to contain_nova_config('DEFAULT/resume_guests_state_on_host_boot').with_value('<SERVICE DEFAULT>') }
+      it { is_expected.to contain_nova_config('compute/cpu_shared_set').with(:value => '<SERVICE DEFAULT>') }
       it { is_expected.to_not contain_nova_config('vnc/novncproxy_base_url') }
       it { is_expected.to contain_nova_config('key_manager/backend').with_value('nova.keymgr.conf_key_mgr.ConfKeyManager') }
       it { is_expected.to contain_nova_config('barbican/barbican_endpoint').with_value('<SERVICE DEFAULT>') }
@@ -75,6 +76,7 @@ describe 'nova::compute' do
           :config_drive_format                => 'vfat',
           :resize_confirm_window              => '3',
           :vcpu_pin_set                       => ['4-12','^8','15'],
+          :cpu_shared_set                     => ['4-12','^8','15'],
           :resume_guests_state_on_host_boot   => true,
           :keymgr_backend                     => 'castellan.key_manager.barbican_key_manager.BarbicanKeyManager',
           :barbican_endpoint                  => 'http://localhost',
@@ -134,6 +136,8 @@ describe 'nova::compute' do
 
       it { is_expected.to contain_nova_config('DEFAULT/vcpu_pin_set').with(:value => '4-12,^8,15') }
 
+      it { is_expected.to contain_nova_config('compute/cpu_shared_set').with(:value => '4-12,^8,15') }
+
       it { is_expected.to contain_nova_config('DEFAULT/max_concurrent_live_migrations').with_value('4') }
 
       it { is_expected.to contain_nova_config('compute/consecutive_build_service_disable_threshold').with_value('9') }
@@ -197,6 +201,16 @@ describe 'nova::compute' do
       end
     end
 
+    context 'when cpu_shared_set is empty' do
+      let :params do
+        { :cpu_shared_set    => ""}
+      end
+
+      it 'clears cpu_shared_set configuration' do
+        is_expected.to contain_nova_config('compute/cpu_shared_set').with(:value => '<SERVICE DEFAULT>')
+      end
+    end
+
     context 'with neutron_enabled set to false' do
       let :params do
         { :neutron_enabled => false }