Writing a LITMUS^RT Scheduler Plugin

In LITMUS, new scheduling policies are implemented as scheduler plugins, which are run in kernelspace. This set of instructions describes how to write a scheduler plugin in LITMUS^RT by re-creating the Partitioned-EDF (P-EDF) scheduler.

Prerequisites

In order to create new scheduler plugins, you must be capable of building the LITMUS^RT kernel from source. If you haven’t already, follow the instructions for building and installing LITMUS^RT.

Steps

The instructions for implementing a new LITMUS^RT scheduler plugin have been separated into 9 steps:

1. Adding an empty source file to the LITMUS^RT kernel
2. Adding stub functions for a LITMUS^RT plugin
3. Creating debug messages using TRACE
4. Defining per-CPU scheduling state for P-EDF
5. Adding P-EDF scheduling logic
6. Task state changes
7. Adding preemption checks
8. Admitting real-time tasks
9. Exporting plugin topology in /proc

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