History Overflow Mechanism
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
In a cache line prediction mechanism, lost history information is preserved in a history overflow buffer (H2) and reloaded into the regular history buffer (H1) when a history pattern in H2 repeats. The disclosed cache line prediction mechanism is based on the next line reference information collected in the past. A history buffer H1 is used at L1 (first level cache). H1 has the same configuration as the L1 directory and may be implemented by adding a field to each entry of L1. For each line in L1, the corresponding entry in H1 contains the next line information (presumably a line ID). A valid bit, attached to each of the entry of H1, indicates the validity of the corresponding next line information. When a line is referenced in L1 with valid next line information, the recorded next line will be prefetched.