Reducing conflict misses using fraction associative mapping

Choice of Degree of Associativity influences many performance parameters such as Silicon Area, Cache Access Time and Miss Rate. Direct Mapping has higher Miss Rate than Set Associative however it has smaller access time. Direct-mapped caches suffer from conflict misses because they lack the associativity to store more than one memory block in each set. Some blocks that have no temporal locality actually may cause program execution degradation by replacing blocks that do manifest temporal behavior. There are various variations of different mapping schemes, which take care of either temporal or spatial locality but not both. This work attempts to design new Cache Mapping Scheme which has cost and performance advantage of Direct Mapping; however its Hit Access Ratio is comparable to Set Associative. This paper describes the design of Fraction Associative Cache, which minimizes the conflicts that arise in direct-mapped accesses by reserving fractional space for conflicting locations; however, it does not affect primary mapped address. Thus this scheme exploits temporal locality without disturbing the spatial locality, at the same time it does not result in under-utilization of memory reserved for resolving conflict misses.