Memory de-duplication
I see you have kernel memory de-duper (called Kernel Same-page Merging, or KSM) available, but it is not currently enabled.
To enable it run:
echo 1 >/sys/kernel/mm/ksm/run
echo 1000 >/sys/kernel/mm/ksm/sleep_millisecs
If you enable it, you will save 40-60% of netdata memory.