An event tracking hardware engine having N (≧2) caches is invoked when an event of interest occurs, using a corresponding key. The engine stores, for each of the different kinds of events, a corresponding cumulative number of occurrences, by carrying out additional steps. In some instances, the additional steps include searching in the N caches for an entry for the key; if an entry for the key is found, and no overflow of the corresponding cumulative number of occurrences for the entry for the key would occur by incrementing the corresponding cumulative number of occurrences, incrementing; if the entry for the key is found, and overflow would occur, promoting the entry to a next highest cache; and if the entry for the key is not found, entering the entry for the key in a zeroth one of the caches with the corresponding cumulative number of occurrences being initialized. In other instances, the additional steps include searching in a zeroth one of the caches for an entry for the key; if an entry for the key is found in the zeroth one of the caches, and no overflow of the corresponding cumulative number of occurrences for the entry for the key would occur by incrementing the corresponding cumulative number of occurrences, incrementing; if the entry for the key is found in the zeroth one of the caches, and overflow would occur, promoting the entry from the zeroth one of the caches in which the entry exists to a next highest cache; and if the entry for the key is not found, entering the entry for the key in the zeroth one of the caches with the corresponding cumulative number of occurrences being initialized. The engine includes a plurality of caches and a corresponding plurality of control circuits.