CHRONOS LINUX

Figure 6 illustrates the global scheduling approach used in ChronOS. In order to implement global scheduling inside ChronOS, we create another level of scheduling abstraction. At the top we have the "global scheduler" which looks at the "global task queue". The global scheduler maps to a "local scheduler" on individual processors which extends from the Linux O(1) scheduler. The global scheduler (invoked on a processor) can either pick a task for itself or decide for all the processors on the system (depending on the scheduling policy used). If the global scheduler needs to choose tasks for all available processors on the system (such as G-EDF, G-GUA or NG-GUA), it picks the top M tasks. These tasks are given to the task mapping algorithm which maps these tasks on M underlying processors. The tasks assigned by the task mapping algorithm are pushed into the "globally assigned task" block from where the "task puller" on each CPU picks up the task and moves it to the head of its local..