A software-SVM-based transactional memory for multicore accelerator architectures with local memory

Abstract

We propose a software transactional memory (STM) for heterogeneous multicores with small local memory. The heterogeneous multicore architecture consists of a general-purpose processor element (GPE) and multiple accelerator processor elements (APEs). The GPE is typically backed by a deep, on-chip cache hierarchy and hardware cache coherence. On the other hand, the APEs have small, explicitly addressed local memory that is not coherent with the main memory. Programmers of such multicore architectures suffer from explicit memory management and coherence problems. The STM for such multicores can alleviate the burden of the programmer and transparently handle data transfers at run time. Moreover, it makes the programmer free from controlling locks. Our TM is based on an existing software SVM for the accelerator architecture. The software SVM exploits software-managed caches and coherence protocols between the GPE and APEs. We also propose an optimization technique, called abort prediction, for the TM. It blocks a transaction from running until the chance of potential conflicts is eliminated. We implement the TM system and the optimization technique for a single Cell BE processor and evaluate their effectiveness with six compute-intensive benchmark applications.