Description of problem:
KSM is not enabled by default on overcloud nodes

Version-Release number of selected component (if applicable):
osp director 8

How reproducible:
100%

Steps to Reproduce:
On a deployed overcloud run the following commands 
1. cat /sys/kernel/mm/ksm/run
2. grep -H '' /sys/kernel/mm/ksm/pages_*
3. systemctl status ksm

Actual results:

# cat /sys/kernel/mm/ksm/run
0
# grep -H '' /sys/kernel/mm/ksm/pages_*
/sys/kernel/mm/ksm/pages_shared:0
/sys/kernel/mm/ksm/pages_sharing:0
/sys/kernel/mm/ksm/pages_to_scan:100
/sys/kernel/mm/ksm/pages_unshared:0
/sys/kernel/mm/ksm/pages_volatile:0
# systemctl status ksm
● ksm.service - Kernel Samepage Merging
   Loaded: loaded (/usr/lib/systemd/system/ksm.service; enabled; vendor preset: enabled)
   Active: active (exited) since Fri 2015-11-20 12:43:50 EST; 2 days ago
 Main PID: 823 (code=exited, status=0/SUCCESS)
   CGroup: /system.slice/ksm.service



Expected results:

[root@overcloud-controller-2 keystone]# cat /sys/kernel/mm/ksm/run
1
[root@overcloud-controller-2 keystone]# grep -H '' /sys/kernel/mm/ksm/pages_*
/sys/kernel/mm/ksm/pages_shared:48911
/sys/kernel/mm/ksm/pages_sharing:90090
/sys/kernel/mm/ksm/pages_to_scan:100
/sys/kernel/mm/ksm/pages_unshared:123002
/sys/kernel/mm/ksm/pages_volatile:1035

non-zero values

Additional info: