Efficient memory modification tracking with hierarchical dirty indicators

摘要

A dirty memory for a computer system is configured hierarchically. This provides for more rapid identification of pages of memory that have been dirtied and require attention. For example for the reintegration of an equivalent memory state to the memories of respective processing sets in a fault tolerant computer following a lockstep error. The dirty memory includes at least two levels. A lower level includes groups of dirty indicators, each dirty indicator being settable to a given state indicative that a page of memory associated therewith has been dirtied. At least one higher level includes dirty group indicators settable to a predetermined state indicative that a group of the lower level associated therewith has at least one dirty indicator in a state indicative that a page of memory associated therewith has been dirtied. There can be more that two layers. Logic controls the operation of the hierarchical dirty memory.