Sharing-aware thread mapping in software transactional memory

• Autor(a) principal: Pasqualin, Douglas Pereira
• Data de Publicação: 2021
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFPel - Guaiaca
• Texto Completo: http://guaiaca.ufpel.edu.br/handle/prefix/7721
• topic: CNPQ::CIENCIAS EXATAS E DA TERRA::CIENCIA DA COMPUTACAO; Computação; Software transactional memory; Sharing-aware; Thread mapping; Communication; Memória transacional em software; Sensibilidade ao compartilhamento; Mapeamento de thread; Comunicação

Software Transactional Memory (STM) is an alternative abstraction for thread synchronization in parallel programming. One advantage is simplicity since it is possible to replace the use of explicit locks with atomic blocks, while the STM runtime is responsible to ensure a consistent execution, for instance, without deadlocks and race conditions. Regarding STM performance, many studies already have been made focusing on reducing the number of transactional aborts and conflicts. However, in current multicore architectures with complex memory hierarchies, it is also important to consider where the memory of a program is allocated and how it is accessed. This thesis proposes the use of a technique called sharing-aware mapping, which maps threads to cores and memory pages to NUMA nodes based on their memory access behavior to achieve better performance in STM systems. The first major contribution of this thesis is a mechanism to detect sharing behavior directly inside the STM library by tracking and analyzing how threads perform STM operations. The collected information can be used to perform an optimized mapping of the application’s threads to cores in order to improve the efficiency of STM operations. The second contribution of this thesis is the characterization of the sharing behavior of STM applications by using information extracted from the STM runtime, providing information to guide thread mapping based on their sharing behavior. The third contribution is a mechanism to perform sharing-aware thread mapping in STM applications. We first introduce Static-SharingAware (SSA), which map threads to cores based on a previous analysis of the sharing behavior of STM applications. Next, we introduce STMap, an online, low overhead mechanism to detect the sharing behavior and perform the mapping directly inside the STM library, by tracking and analyzing how threads perform STM operations during the execution. In experiments with the STAMP benchmark suite and synthetic benchmarks, both mechanisms showed performance gains when compared to the default Linux scheduler.