Vector class on Limited Local Memory (LLM) multi-core processors

Limited Local Memory (LLM) multi-core architecture is a promising solution for scalable memory hierarchy. LLM architecture, e.g., IBM Cell/B.E. is a purely distributed memory architecture in which each core can directly access only its small local memory, and that is why it is extremely power-efficient. Vector is a popular container class in the C++ Standard Template Library (STL), which provides the functionality similar to a dynamic array. Due to the small non-virtualized memory in the LLM architecture, vector library implementation cannot be used as it is. In this paper, we propose and implement a scheme to manage vector class in the local memory present in each core of LLM multi-core architecture. Our scalable solution can transparently maintain vector data between the shared global memory and the local memories. In addition, different data transfer granularities are provided by our vector class to achieve better performance. We also propose a mechanism to ensure the validity of pointers-to-elements when the vector elements are moved into the global memory. Experimental result shows that our vector class can improve the programmability of vector class significantly while the overhead can be contained within 7%.