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This paper explores the problem of how to improve the average-case performance of real-time locking protocols, preferably without significantly deteriorating worst-case performance. Motivated by the futex implementation in Linux, where uncontended lock operations under the Priority Inheritance Protocol (PIP) do not incur mode-switching overheads, we extend this concept to more sophisticated protocols; namely the PCP, the MPCP and the FMLP + . We identify the challenges involved in implementing futexes for these protocols and present the design and evaluation of their implementations in LITMUS RT , a real-time extension of the Linux kernel. Our evaluation shows substantial improvements in the uncontended case (e.g., a futex implementation of the PCP lowers lock acquisition and release overheads by up to 75% and 92%, respectively), at the expense of some increases in worst-case overhead on par with Linux's existing futex implementation.

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We show how to efficiently solve energy Büchi problems in finite weighted Büchi automata and in one-clock weighted timed Büchi automata; all our algorithms are implemented in a pipeline based on TChecker and Spot. Solving the latter problem is done by using the corner-point abstraction; the former problem is handled by a modified version of Bellman-Ford interleaved with Couvreur's algorithm.