Preempt tasks with lower priority

[mateuszlitwin]

Is this a BUG REPORT or FEATURE REQUEST?:

/kind feature

Description:

You should be able to configure kube-batch, so it preempts tasks of lower priority jobs when higher priority job arrives. Based on the code I read and what I observed on the cluster it looks like there is no way to enforce that. It looks like only gang, drf and conformance provide "preemptable functions".

Possible solution is to add preemptable function to priority plugin:

preemptableFn := func(preemptor *api.TaskInfo, preemptees []*api.TaskInfo) []*api.TaskInfo {
	preemptorJob := ssn.Jobs[preemptor.Job]
	var victims []*api.TaskInfo
	for _, preemptee := range preemptees {
		preempteeJob := ssn.Jobs[preemptee.Job]
		if preempteeJob.Priority >= preemptorJob.Priority {
			glog.V(3).Infof("Can not preempt task <%v/%v> because "+
				"preemptee has greater or equal job priority (%d) than preemptor (%d)",
				preemptee.Namespace, preemptee.Name, preempteeJob.Priority, preemptorJob.Priority)
		} else {
			victims = append(victims, preemptee)
		}
	}
	glog.V(3).Infof("Victims from Priority plugins are %+v", victims)
	return victims
}
ssn.AddPreemptableFn(pp.Name(), preemptableFn)

Let me know if this make sense.

[k82cn]

yes, that makes sense to me :)