I would like to define a policy to dynamically assigns resource limits to pods and containers. For example, if there are 4 number of pods scheduled in a specific node, and the memory capacity is 100mi, each pod to be assigned with 25mi memory limit. In other words, the fair share of the node capacity.
So, is it necessary to change the codes in scheduler.go or I need to change other objects as well?
I think this is contrary to the ideology of the kubernetes. In this approach, the new application will not be able to get to the node. At each point in time for the scheduler will be the utilization of 100% each node.
I do agree with Arslanbekov answer, it's contrary to the ideology of scalability used by kubernetes.
The principle is that you define what resources is needed by your application and the cluster do all it can to give this resource to the pod, scalling the resources (pod, nodes) depending on the global consumption of all apps.
What you are asking is the reverse, give resources to the pod depending on the node resources, this way could prove very difficult to allow automatic scallability of the nodes as it would be the resource aim to attain (I may be confusing in my explanation but that shows how difficult it could be).
One way to do what you want would be to size all your pod to the same size to use 80% of the nodes but this would prove wrong if an app need more resources.