Preemption for Coscheduling #581
Description
I noticed that when using coscheduling, preempt only one pod a time is not enough.
So I am considering about implement a plugin to support preempt more than one pod a time.
I have implemented a prototype of batch preemption. The batch preemption plugin (will be called BP) will interact with other plugin. BP provide an interface with 2 functions for other plugins: 1. to query the list of pods ready for preemption and 2. do preemption if current pod schedule successfully or preempt successfully.
If a pod find some victims on a node, the plugin will record the result and do nothing.If some other plugins decide to do the preemption after a successful scheduling or successful preemption, they can call the interface, then BP will preempt all victims it has recorded.
Of course, the prototype has already taken into account the situation where the Pod in the record is preempted again by other Pods, or the Pod in the record is rescheduled. This is a bit complicated. If necessary, I will add it later
The point is that I believe the user interaction in the prototype is unreasonable.
In the prototype, BP's behavior is hard coded. I think we may need a CRD for BP to decide when to do preemption. Do you have some ideas?