HaVOC: A hybrid memory-aware virtualization layer for on-chip distributed ScratchPad and Non-Volatile Memories

Hybrid on-chip memories that combine Non-Volatile Memories (NVMs) with SRAMs promise to mitigate the increasing leakage power of traditional on-chip SRAMs. We present HaVOC: a run-time memory manager that virtualizes the hybrid on-chip memory space and supports efficient sharing of distributed ScratchPad Memories (SPMs) and NVMs. HaVOC allows programmers and the compiler to partition the application´s address space and generate data/instruction block layouts considering virtualized hybrid address spaces. We define a data volatility metric used by our hybrid memory-aware compilation flow to generate memory allocation policies that are enforced at run-time by a filter-inspired dynamic memory algorithm. Our experimental results with a set of embedded benchmarks executing simultaneously on a Chip-Multiprocessor with hybrid NVM/SPMs show that HaVOC is able to reduce execution time and energy by 60.8% and 74.7% respectively with respect to traditional multitasking based SPM allocation policies.