From 1b9a26d814dd3e12a9b355bca7d63806167c72e3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Max=20H=C3=B6sel?= <git@maxhoesel.de>
Date: Thu, 14 Jul 2022 20:41:11 +0200
Subject: [PATCH] add cpu governor settings to pve role (#37)

---
 roles/pve/README.md         | 15 +++++++++++++++
 roles/pve/defaults/main.yml |  3 +++
 roles/pve/tasks/cpu.yml     | 15 +++++++++++++++
 roles/pve/tasks/main.yml    |  2 ++
 4 files changed, 35 insertions(+)
 create mode 100644 roles/pve/tasks/cpu.yml

diff --git a/roles/pve/README.md b/roles/pve/README.md
index be57edb..f98e7ea 100644
--- a/roles/pve/README.md
+++ b/roles/pve/README.md
@@ -22,3 +22,18 @@ the underlying system. Right now, it manages the root users password and configu
 - Choices: `enterprise`, `no-subscription`, `test`
 - Please note that this role does not configure your subscription key, you will have to do so yourself
 - Default: `no-subscription`
+
+##### `pve_set_cpu`
+- Whether to modify the CPU configuration, such as the chosen governor.
+- Default: `false`
+
+##### `pve_cpu_governor`
+- Which CPU governor to use for all CPU cores on each node
+- You can check which CPU governors are available for your CPU and driver by running
+  `cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors` on one of your nodes.
+  - The `intel_pstate` driver hands much of the CPU scaling off to the hardware and only supports two governors - `powersave` and `performance`.
+    See the [kernel docs](https://www.kernel.org/doc/html/v4.19/admin-guide/pm/intel_pstate.html) for more information.
+  - Older Intel CPUs under (`intel_cpufreq`) and AMD CPUs can use any [generic governor](https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt).
+  - Proxmox defaults to `performance` due to potential [BSODs in Windows guests when running with variable frequency](https://forum.proxmox.com/threads/windows-7-x64-vms-crashing-randomly-during-process-termination.18238/#post-93273)
+  - `ondemand` and `schedutil` both scale CPU frequency dynamically and may improve power consumption.
+- Default: `performance`. Set to `schedutil` if you want to save power and aware of the limitations mentioned above.
diff --git a/roles/pve/defaults/main.yml b/roles/pve/defaults/main.yml
index ce0cbbc..996a4e8 100644
--- a/roles/pve/defaults/main.yml
+++ b/roles/pve/defaults/main.yml
@@ -1 +1,4 @@
 pve_repo_type: no-subscription
+
+pve_set_cpu: no
+pve_cpu_governor: performance
diff --git a/roles/pve/tasks/cpu.yml b/roles/pve/tasks/cpu.yml
new file mode 100644
index 0000000..3911a97
--- /dev/null
+++ b/roles/pve/tasks/cpu.yml
@@ -0,0 +1,15 @@
+- name: intel-cpupower is installed
+  ansible.builtin.apt:
+    name: linux-cpupower
+
+- name: Get current governor
+  ansible.builtin.shell: "cat /sys/devices/system/cpu/cpu[0-9]*/cpufreq/scaling_governor"
+  changed_when: no
+  check_mode: no
+  register: _pve_current_governor
+
+- name: Set CPU governor to {{ pve_cpu_governor }}
+  ansible.builtin.command: "cpupower frequency-set -g {{ pve_cpu_governor }}"
+  when: >
+    (_pve_current_governor.stdout_lines | unique | select | list).0 != pve_cpu_governor or
+    (_pve_current_governor.stdout_lines | unique | select | list | length) > 1
diff --git a/roles/pve/tasks/main.yml b/roles/pve/tasks/main.yml
index d2f0f04..72c43c4 100644
--- a/roles/pve/tasks/main.yml
+++ b/roles/pve/tasks/main.yml
@@ -13,3 +13,5 @@
     password: "{{ pve_root_password | password_hash('sha512', 65534 | random(seed=inventory_hostname) | string) }}"
 
 - include_tasks: repo.yml
+- include_tasks: cpu.yml
+  when: pve_set_cpu