Prompt application-transparent transaction revalidation in software transactional memory

Abstract

Software Transactional Memory (STM) allows encapsulating shared-data accesses within transactions, executed with atomicity and isolation guarantees. The assessment of the consistency of a running transaction is performed by the STM layer at specific points of its execution, such as when a read or write access to a shared object occurs, or upon a commit attempt. However, performance and energy efficiency issues may arise when no shared-data read/write operation occurs for a while along a thread running a transaction. In this scenario, the STM layer may not regain control for a considerable amount of time, thus not being able to early detect if such transaction has become inconsistent in the meantime. To tackle this problem we present an STM architecture that, thanks to a lightweight operating system support, is able to perform a fine-grain periodic (hence prompt) revalidation of running transactions. Our proposal targets Linux and x86 systems and has been integrated with the open source TinySTM package. Experimental results with a port of the TPC-C benchmark to STM environments show the effectiveness of our solution.

Design and implementation of a fully transparent partial abort support for software transactional memory

“…Many proposals focus on designing, optimizing, or tuning the conflict detection and management algorithms used by STM implementations. 4,[8][9][10][11][12]17 Other studies proposed compiler-based and runtime techniques which use statistics collected at runtime to identify performance bottlenecks and to guide tuning decisions (e.g., Wu et al 25 ). Further, autonomic-computing approaches for mapping threads to the different cores in multi-core machines, as well as machine learning-based techniques for improving the performance of STM application at runtime have been studied (e.g., Xiao et al 26 and Zhou et al 27 ).…”

“…In particular, the latter aspect requires the programmer's care to write transactional code that is idempotent in writing thread-private data, thus increasing the complexity level. Concerning the performance issue, a great effort has been made by researchers to limit the performance impact of STM and to improve the STM performance through various approaches, spanning from alternative conflict detection and resolution algorithms, 4,[8][9][10][11] to dynamic concurrency control and dynamic tuning, 12,13 and to transaction scheduling techniques. [14][15][16][17][18][19][20][21][22] However, one approach that has been less explored is the partial abort of transactions, particularly with the goal of designing effective runtime mechanisms to make this approach viable and transparent on off-the-shelf systems.…”

Model-Based Proactive Read-Validation in Transaction Processing Systems

“…In [12] the transaction validity check is triggered periodically, via an ad-hoc operating system support integrated within Linux. Differently from this proposal, our model-based readvalidation scheme does not need special support within the operating system, thus being of wider applicability.…”

“…Differently from this proposal, our model-based readvalidation scheme does not need special support within the operating system, thus being of wider applicability. Also, the solution in [12] does not rely on any prediction scheme for choosing at which points to attempt transaction validation. The validation task is triggered independently of the probability that the transaction has become invalid.…”