KVM enable memory page merging

1 intro

It is easy to enable kvm. However, the defaults are fairly conservative.

1.1 howto enable

vi /etc/rc.local

# ksm page merging, default 0
echo 1 > /sys/kernel/mm/ksm/run
# pages to scan on each run, default: 100
echo 1000 > /sys/kernel/mm/ksm/pages_to_scan
# time to sleep after each scan, default: 200
echo 20 > /sys/kernel/mm/ksm/sleep_millisecs

chmod +x /etc/rc.d/rc.local

1.2 load tuning

free -t | grep ^Mem: | awk '{print $7/1024 " MB"}'
top # sort for cpu with "P" and look for ksmd