Performance-oriented applications require efficient locks to harness the computing power of multicore architectures. While fast, spinlock algorithms suffer severe performance degradation when thread counts exceed available hardware capacity, i.e., in oversubscribed scenarios. Existing solutions rely on imprecise heuristics for blocking, leading to suboptimal performance. We present FlexGuard, the first approach that systematically switches from busy-waiting to blocking precisely when a lock-holding thread is preempted. Flex-Guard achieves this by communicating with the OS scheduler via eBPF, unlike prior approaches. FlexGuard matches or improves performance in LevelDB, a memory-optimized database index, PARSEC's Dedup, and SPLASH2X's Raytrace and Streamcluster, boosting throughput by 1–6× in non-oversubscribed and up to 5× in oversubscribed scenarios.

The pressing demand to deploy software updates without stopping running programs has fostered much research on live update systems in the past decades. Prior solutions, however, either make strong assumptions on the nature of the update or require extensive and error-prone manual effort, factors which discourage the adoption of live update. This paper presentsMutable Checkpoint-Restart(MCR), a new live update solution for generic (multiprocess and multithreaded) server programs written in C. Compared to prior solutions, MCR can support arbitrary software updates and automate most of the common live update operations. The key idea is to allow the running version to safely reach a quiescent state and then allow the new version to restart as similarly to a fresh program initialization as possible, relying on existing code paths to automatically restore the old program threads and reinitialize a relevant portion of the program data structures. To transfer the remaining data structures, MCR relies on a combination of precise and conservative garbage collection techniques to trace all the global pointers and apply the required state transformations on the fly. Experimental results on popular server programs (Apache httpd,nginx,OpenSSHandvsftpd) confirm that our techniques can effectively automate problems previously deemed difficult at the cost of negligible performance overhead (2 percent on average) and moderate memory overhead (3.9$\times$on average, without optimizations).

GentleRain is a new causally consistent geo-replicated data store that provides throughput comparable to eventual consistency and superior to current implementations of causal consistency.

The pressing demand to deploy software updates without stopping running programs has fostered much research on live update systems in the past decades. Prior solutions, however, either make strong assumptions on the nature of the update or require extensive and error-prone manual effort, factors which discourage live update adoption.