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Modern implementations of DBMS software are intended to take advantage of high core counts that are becoming common in high-end servers. However, we have observed that several database platforms, including MySQL, Shore-MT, and a commercial system, exhibit throughput collapse as load increases into oversaturation (where there are more request threads than cores), even for a workload with little or no logical contention for locks, such as a read-only workload. Our analysis of MySQL identifies latch contention within the lock manager as the bottleneck responsible for this collapse. We design a lock manager with reduced latching, implement it in MySQL, and show that it avoids the collapse and generally improves performance. Our efficient implementation of a lockmanager is enabled by a staged allocation and deallocation of locks. Locks are preallocated in bulk, so that the lock manager only has to perform simple list manipulation operations during the acquire and release phases of a transaction. Deallocation of the lock data structures is also performed in bulk, which enables the use of fast implementations of lock acquisition and release as well as concurrent deadlock checking. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this research is to compare an industrial ethernet based network (PROFINET Class 1) with a traditional fieldbus network (PROFIBUS). Design/methodology/approach – Two sets of identical motors were used in the experimental set-up. The speed synchronisation of a lead and follower motors was compared using both PROFINET Class 1 and a PROFIBUS DP network. The level of synchronising achievable was used as a measure of performance for each network. Findings – It was found that PROFIBUS DP produces a better performance for set point and load changes than PROFINET Class 1 network. Research limitations/implications – PROFINET Class 2 and higher could not be used in the experiment due to availability of equipment and funding. Practical implications – This research provides a comparative study of two very popular industrial networks. The results can be used as reference by industry for selection of industrial networks. Originality/value – The paper provides a manufacturer independent practical comparison of two industrial networks. The application area of speed synchronisation is demanding, and should inform the user on the performance and limitation of industrial networks. [ABSTRACT FROM AUTHOR]

We present a novel framework for automatic inference of efficient synchronization in concurrent programs, a task known to be difficult and error-prone when done manually. Our framework is based on abstract interpretation and can infer synchronization for infinite state programs. Given a program, a specification, and an abstraction, we infer synchronization that avoids all (abstract) interleavings that may violate the specification, but permits as many valid interleavings as possible. Combined with abstraction refinement, our framework can be viewed as a new approach for verification where both the program and the abstraction can be modified on-the-fly during the verification process. The ability to modify the program, and not only the abstraction, allows us to remove program interleavings not only when they are known to be invalid, but also when they cannot be verified using the given abstraction. We implemented a prototype of our approach using numerical abstractions and applied it to verify several example programs. [ABSTRACT FROM AUTHOR]

Abstract: This note addresses a controlled synchronization problem for chaotic systems involving a communication network with data packet dropout. A chaotic master system and its slave system are connected with a controller via a limited channel and data packet dropout is modeled as Bernoulli process. Then, a coder–decoder pair is designed with the controller such that the master system and the slave system are completely synchronized, not necessarily bounded for synchronization. Necessary data capacity of a channel is explicitly stated. Finally, a numerical example for the 3-double-scroll chaotic system is applied to illustrate the effectiveness of the obtained result. [Copyright &y& Elsevier]

Abstract: Lock synchronization is a key programming primitive for shared-memory many-core CMPs. However, as the number of cores increases, conventional software implementations cannot meet the desirable levels of performance and scalability. Meanwhile, most existing hardware-supported lock proposals require modifications at some level of the memory hierarchy, thus degrading QoS of applications through synchronization traffic. In this paper, we propose GLock, a dedicated network infrastructure and a token-based message-passing protocol to provide a non-intrusive, extremely efficient and fair implementation for highly contended locks. Two implementations of GLock are considered. The first leverages current full-custom G-lines technology, whilst the second uses a cost-effective mainstream industrial toolflow with an advanced 45 nm technology. When compared with the most efficient software-based lock, both alternatives provide significant reductions in execution time, network traffic and power consumption, for a representative set of benchmarks, with negligible area overhead. [Copyright &y& Elsevier]