From 55be5746305fbf3799535b2072e941ca8f7901e4 Mon Sep 17 00:00:00 2001
From: Marc Gariepy <gariepy.marc@gmail.com>
Date: Thu, 26 Oct 2017 10:06:45 -0400
Subject: [PATCH] Explicitly disable KSM by default on Ubuntu.

By default KSM is enabled on Ubuntu, disabling it specificaly.

Change-Id: I689a851c5268db70e04564386952945fe5612cb0
---
 .../notes/disable-ksm-670aeb175826b7ca.yaml        |  5 +++++
 tasks/drivers/kvm/nova_compute_kvm.yml             | 14 ++++++++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 releasenotes/notes/disable-ksm-670aeb175826b7ca.yaml

diff --git a/releasenotes/notes/disable-ksm-670aeb175826b7ca.yaml b/releasenotes/notes/disable-ksm-670aeb175826b7ca.yaml
new file mode 100644
index 00000000..cd7b61cd
--- /dev/null
+++ b/releasenotes/notes/disable-ksm-670aeb175826b7ca.yaml
@@ -0,0 +1,5 @@
+---
+upgrade:
+  - KSM configuration is changed to disabled by default on Ubuntu.
+    if you overcommit the RAM on your hypervisor it's a good
+    idea to set ``nova_compute_ksm_enabled`` to True.
diff --git a/tasks/drivers/kvm/nova_compute_kvm.yml b/tasks/drivers/kvm/nova_compute_kvm.yml
index 6067648c..fdc2e685 100644
--- a/tasks/drivers/kvm/nova_compute_kvm.yml
+++ b/tasks/drivers/kvm/nova_compute_kvm.yml
@@ -113,6 +113,20 @@
     - nova-kvm
     - nova-libvirt
 
+- name: Set qemu-kvm KSM config (Ubuntu)
+  lineinfile:
+    dest: "/etc/default/qemu-kvm"
+    line: "KSM_ENABLED={{ nova_compute_ksm_enabled | ternary('1','0') }}"
+    regexp: "^KSM_ENABLED=*"
+    backup: yes
+  when:
+    - ansible_pkg_mgr == 'apt'
+  notify: Restart libvirt-bin
+  tags:
+    - nova-config
+    - nova-kvm
+    - nova-libvirt
+
 - include: nova_disable_smt.yml
   when:
     - ansible_architecture == 'ppc64le'