Not a single sentence of mine has a subject other than &quot;Berkeley DB&quot; or &quot;it&quot;.  I&#x27;m completely baffled how you read anything categorical from my post.<p>&quot;More likely&quot; is not documentation, when you need guarantees that certain pages are not evicted in favor of others.  (If my memory of the source code serves me, these levels map to internal values that have some nonlinear relationship with some LRU cache parameter, with the highest priority effectively locking pages into cache, except for certain cases which I forget.)<p>Also, the powers-of-two phrase is a recent addition: <a href="http:&#x2F;&#x2F;web.stanford.edu&#x2F;class&#x2F;cs276a&#x2F;projects&#x2F;docs&#x2F;berkeleydb&#x2F;api_c&#x2F;env_set_cachesize.html" rel="nofollow">http:&#x2F;&#x2F;web.stanford.edu&#x2F;class&#x2F;cs276a&#x2F;projects&#x2F;docs&#x2F;berkeleyd...</a>