Selective scanning of overlap-table in storage memories

Abstract

Scanning overlap tables for data that is present in cache, but not yet written to the memory device, is time consuming. Performance requirements are increasing as is the size of the overlap table. With the increased size of the overlap table comes a reduction in speed to obtain results of a scan which leads to challenges meeting performance requirements. By providing a cache occupation bitmap, scans can be reduced. Rather than scanning the entire overlap table, a cache occupation bitmap can be searched. When executing a read command, only if the cache occupation bitmap contains an indication that the overlap table has cache data within a range that encompasses the data correlating to the read command will the overlap table be search. In so doing, the overlap table need not be searched when executing every read command, thus allowing achievement of performance requirements more realistic.