roles/vmhost: Enable KSM

This commit adds a systemd unit to enable the Kernel Same-page Merging
daemon on VM hosts. This allows much greater virtual machine density,
especially when many VMs are running the same guest OS.

roles/vmhost/tasks/main.yml

@@ -69,3 +69,18 @@
     immediate=yes
     state=enabled
   notify: save firewalld configuration
+
+- name: ensure systemd ksm unit is installed
+  copy:
+    src=ksm.service
+    dest=/etc/systemd/system/ksm.service
+    mode=0644
+  notify: reload systemd
+- name: ensure systemd ksm unit starts at boot
+  service:
+    name=ksm
+    enabled=yes
+- name: ensure systemd ksm unit is running
+  service:
+    name=ksm
+    state=started