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Announcement - Agenda - Paper Presentations

(Please consider this submission even though it is a little late. Each of two co-authors thought the other had submitted this on time. We are really sorry for this mistake.) This paper reports on the current status of a Linux-based system being developed at the University of North Carolina called LITMUS-RT (LInux Testbed for MUltiprocessor Scheduling in Real-Time systems). The development of LITMUS-RT was motivated by a number of recent research breakthroughs in work on multiprocessor real-time scheduling algorithms. In short, this work has shown that global algorithms (which schedule tasks from a single run queue) have a number of advantages of partitioning approaches. This is mainly due to the bin-packing-like limitations to which partitioning approaches are subject when checking schedulability. LITMUS-RT extends Linux (currently, version 2.6.20) by allowing different multiprocessor real-time scheduling and synchronization policies to be specified (at boot time) as plugin components. To the best of our knowledge, LITMUS-RT is the only (published) system wherein global multiprocessor real-time scheduling algorithms are implemented in a real operating system. An emprical comparison of such algorithms on LITMUS-RT was presented at RTSS 2006. In recent work, LITMUS-RT was extended to support a new real-time locking protocol called the flexible multiprocessor locking protocol (FMLP). The FMLP is the only (published) real-time locking protocol known to us that can be used under global scheduling algorithms. An empirical comparison of spin-based locking, suspension-based locking, and non-blocking synchronization was recently conducted on LITMUS-RT and is currently in submission elsewhere. This paper summarizes on these prior efforts and also discusses future planned extensions of LITMUS-RT.