Lets you specify two things
Configure Percentage of node capacity that should be allocated when a job runs on particular node
Configure if only one instance of a job can run on a given node at any given time
This plugin adds two new options to job config page
1.Needs percentage based access to slave's resources
For example if you specify a job to take 50% of node's capacity and the node is configured to use 6 executors. When this job runs on the node it would only allocate jobs on the 3 remaining executors and allocate 3 executors to this job.
2.Can run only single instance per slave
If you check this option only one job would be scheduled per node