Testing Linux-based real-time systems: Lachesis

Testing is a key step in the software development cycle. Errors and bug fixing costs can significantly affect development costs without a full and comprehensive test on the system. Testing is even more important in real-time systems, because they are used in environments where a single failure could lead to serious damages. The first efforts to change the Linux kernel, introducing in it some real-time features, are dating back more than ten years ago. Nevertheless, up to now there's not a comprehensive test suite able to assesses the functionality and the conformance to the real-time operating systems standards for the Linux kernel and for the real-time nanokernels that rely on it. This paper discusses an ongoing work on Lachesis, an automated test suite for real-time Linux features. Lachesis's main goals are: to provide a standard and simple API to develop new tests; to provide a set of functional, regression, performance and stress test, either developing or porting them from other test suites; to design and experiment a series of build tests; to make the test suite extensible and portable. Up to now Lachesis is used to test Linux, PREEMPT RT, RTAI and Xenomai real-time features and performances. It provides some tests for SCHED DEADLINE patch, too. Lachesis is under active development: extensions to other real-time systems and more tests are planned to be added in the near future.