Handling Multi-path Hierarchies

Since PROMOTE does not significantly alter the local caching policy, extensions to multi-path hierarchies is as simple as requiring that the caches with multiple directly connected higher caches maintain a separate $probPromote$ value corresponding to each such higher cache, and that hints be sent to all directly connected lower caches. It may not always be possible to equalize the cache lives or marginal utilities, however, merely allowing the adaptation to attempt the equalization results in better performance.

On the other hand, it is difficult to conceive a multi-path version of DEMOTE in many cases (e.g. ARC hierarchies in Figures 14 and 15). Hence, PROMOTE is not only easier to apply to multi-level caches than DEMOTE, it is also more broadly applicable.