A Data Cache with Dynamic Mapping

Dynamic Mapping is an approach to cope with a loss of performance due to cache interference and to improve performance predictability of blocked algorithms for modern architectures. An example is matrix multiply: tiling matrix multiply for a data cache of 16KB using optimal tiles size achieves an average data-cache miss rate of 3%, but with peaks of 16% due to interference. Dynamic Mapping is a software-hardware approach for which the mapping in cache is determined at compile time, by manipulating the address used by the data cache. The reduction in the cache misses translates into a 2-fold speed-up for matrix multiply and FFT by eliminating data-cache miss spikes. Dynamic mapping has the same goal as other proposed approaches, but it determines the cache mapping before issuing a load. It uses the computational power of the processor instead of the memory controller or the data cache mapping and it has no effect on the access time in memory and cache. It is an approach combining several concepts, such as nonstandard cache mapping functions and data layout reorganization and, potentially, without any overhead.