Sanctions - time based cache - tuning saving - and - techniques replacement

摘要

Cache data replacement techniques enable improved performance in a computer system having a central processing unit (CPU), a cache memory and a main memory, wherein the cache memory has a plurality of data items stored therein. The cache data replacement techniques include associating a priority value with each of the stored data items, wherein for each data item, the priority value is an estimate of how much CPU stall time will occur if an attempt is made to retrieve the data item from the cache memory when the data item is not stored in the cache memory. When a cache entry must be replaced, the priority values are analyzed to determine a lowest priority value. One of the data items that has the lowest priority value is selected and replaced by a replacement data item. The priority value of a data item may be determined, as a function of how many other instructions have been fetched and stored in a buffer memory between a time interval defined by initiation and completion of retrieval of the data item from the main memory, wherein execution of the other instruction is dependent on completing retrieval of the data item. In other aspects of the invention, the priority values of cache entries may periodically be lowered in order to improve the cache hit ratio, and may also be reinitialized whenever the associated data time is accessed, in order to ensure retention of valuable data items in the data cache.