Apparatus and methods to reduce castouts in a multi-level cache hierarchy

摘要

Techniques and methods are used to control allocations of cache lines to a higher level cache that have been displaced from a lower level cache. The allocations of the displaced cache lines are prevented for displaced cache lines that are determined to be redundant in the next level cache, whereby the displaced cache line castouts are not allocated to the higher level cache. To such ends, a line is selected to be displaced in a lower level cache. Information associated with the selected line is identified which indicates that the selected line is present in a higher level cache. An allocation of the selected line in the higher level cache is prevented based on the identified information.