Micro-transactions for concurrent data structures

Transactional memory is a promising technique for enforcing disciplined access to shared data in a multiprocessor system. Transactional memory simplifies the implementation of a variety of concurrent data structures. In this paper, we study the benefits of a modest, real-time aware, hardware implementation of transactional memory that we call micro-transactions. In particular, we argue that hardware support for micro-transactions allows us to efficiently implement certain data structures. Those data structures are difficult to realize with the atomic operations provided by stock hardware and provide real-time guarantees for those operations. Our main implementation platform is the Java Optimized Processor system, a field-programmable gate array (FPGA) implementation of the Java virtual machine, optimized for real-time Java. We report on the performance of data structures implemented with locks, atomic instructions, and micro-transactions. Our results suggest that transactional memory is an interesting alternative to traditional concurrency control mechanisms.