Josef Ezra - Ashland MA, US
EMC Corporation - Hopkinton MA
A method for estimating the fall through time of a cache includes maintaining local statistics associated with each data cache slot replaced by a processor, reading from a memory global statistics related to each data cache slot replaced by a plurality of processors, calculating new global statistics, and estimating a fall through time of the cache in response to the global statistics at a predetermined rate. When the global statistics are the result of at least a threshold number of data cache slots having been replaced, the new global statistics are calculated by weighting the global statistics by a factor of less than one and adding the weighted global statistics to the local statistics. When the global statistics are not the result of at least a threshold number of data cache slots having been replaced, the new global statistics are calculated by adding a time related to the lapsed time to a global sum value associated with the time stamp difference of the replaced data cache slots. In a multi-processor computer system, each of the processors accesses the global memory to update the global statistics at a different time.