[all] Allow tweaking watermarks through config files

[mocchira]

received a request as below.

Would it be possible (and meaningful) to allow tweaking watermarks though config files? E.g. rabbitmq allows that, which is really useful for running in container where amount of physical memory seen by erlang isn't the same as amount allocated to this container.

and rabbitmq's approach is here https://www.rabbitmq.com/memory.html

[mocchira]

There are two ways to solve this issue.

• Implement the original vm monitoring feature like rabbitmq
  • https://github.com/rabbitmq/rabbitmq-server/blob/8bf65e52fc2e5a6242197f8364d2ec0dd3b60145/src/vm_memory_monitor.erl
• Use the memsup built-in erlang runtime
  • http://erlang.org/doc/man/memsup.html