Controls how Jenkins schedules builds on this node.

Use this node as much as possible
  This is the default setting.
  In this mode, Jenkins uses this node freely. Whenever there is a build that can be done by using this node, Jenkins will use it.
Only build jobs with label expressions matching this node
  In this mode, Jenkins will only build a project on this node when that project is restricted to certain nodes using a label expression, and that expression matches this node's name and/or labels.

  This allows a node to be reserved for certain kinds of jobs. For example, if you have jobs that run performance tests, you may want them to only run on a specially configured machine, while preventing all other jobs from using that machine. To do so, you would restrict where the test jobs may run by giving them a label expression matching that machine.
  Furthermore, if you set the # of executors value to 1, you can ensure that only one performance test will execute at any given time on that machine; no other builds will interfere.