Reducing the Impact of the MemoryWall for I/O Using Cache Injection

Cache injection addresses the continuing disparity between processor and memory speeds by placing data into a processor´s cache directly from the I/O bus. This disparity adversely affects the performance of memory bound applications including certain scientific computations, encryption, image processing, and some graphics applications. Cache injection can reduce memory latency and memory pressure for I/O. The performance of cache injection is dependent on several factors including timely usage of data, the amount of data, and the application´s data usage patterns. We show that cache injection provides significant advantages over data prefetching by reducing the pressure on the memory controller by up to 96%. Despite its benefits, cache injection may degrade application performance due to early injection of data. To overcome this limitation, we propose injection policies to determine when and where to inject data. These policies are based on OS, compiler, and application information.