Chip-multiprocessors are quickly becoming popular in embedded systems. However, the practical success of CMPs strongly depends on addressing the difficulty of multithreaded application development for such systems. Transactional memory (TM) promises to simplify concurrency management in multithreaded applications by allowing programmers to specify coarse-grain parallel tasks, while achieving performance comparable to fine-grain lock-based applications. This paper presents ATLAS, the first prototype of a CMP with hardware support for transactional memory. ATLAS includes 8 embedded PowerPC cores that access coherent shared memory in a transactional manner. The data cache for each core is modified to support the speculative buffering and conflict detection necessary for transactional execution. The authors have mapped ATLAS to the BEE2 multi-FPGA board to create a full-system prototype that operates at 100MHz, boots Linux, and provides significant performance and ease-of-use benefits for a range of parallel applications. Overall, the ATLAS prototype provides an excellent framework for further research on the software and hardware techniques necessary to deliver on the potential of transactional memory

Chip-multiprocessors are quickly gaining momentum in all segments of computing. However, the practical success of CMPs strongly depends on addressing the difficulty of multithreaded application development. To address this challenge, it is necessary to co-develop new CMP architecture with novel programming models. Currently, architecture research relies on software simulators which are too slow to facilitate interesting experiments with CMP software without using small datasets or significantly reducing the level of detail in the simulated models. An alternative to simulation is to exploit the rich capabilities of modern FPGAs to create FPGA-based platforms for novel CMP research. This paper presents ATLAS, the first prototype for CMPs with hardware support for Transactional Memory (TM), a technology aiming to simplify parallel programming. ATLAS uses the BEE2 multi-FPGA board to provide a system with 8 PowerPC cores that run at 100MHz and runs Linux. ATLAS provides significant benefits for CMP research such as 100x performance improvement over a software simulator and good visibility that helps with software tuning and architectural improvements. In addition to presenting and evaluating ATLAS, we share our observations about building a FPGA-based framework for CMP research. Specifically, we address issues such as overall performance, challenges of mapping ASIC-style CMP RTL on to FPGAs, software support, the selection criteria for the base processor, and the challenges of using pre-designed IP libraries.