software-managed memory

An SPE’s local store (LS), which is filled from main memory using software-initiated DMA transfers. Although most processors reduce latency to memory by using caches, an SPE uses its DMA-filled LS. This approach provides a high degree of control for real-time programming. However, this approach is advantageous only if the DMA transfer-size is sufficiently large and the DMA command is issued well before the data is needed, because the latency and instruction overhead associated with DMA transfers exceeds the latency of servicing a cache miss.