A memory management system determines a timestamp for a memory access operation that accesses a block of data, and uses the timestamp to access a timestamp-indexed record. The timestamp-indexed record includes a plurality of record arrays, each of which corresponds to a different time range, and includes one or more record entries of a different array-specific time duration. The system selects a record entry that indicates a time range associated with the timestamp, and that indicates an amount of memory accessed during the indicated time range. The system then updates the selected record entry to account for the memory size of the block of data.