1. A computer system comprising: a cache hierarchy including a first cache at a first level to store a plurality of items, and a second cache at a second level higher than the first level, wherein: the computer system is to apply a coherency protocol in which any of the items stored in the first cache is assigned to an uncached class if the respective item has been evicted from the second cache, and the computer system is further to evict one of the items from the first cache, wherein the computer system is not to evict from the first cache any of the items in a cached class when any of the items stored in the first cache is in the uncached class.