> Is there a known reason why the LRU reference age for an LRU cache > directory sometimes jumps up and down between two levels that > differ by several days? For example my cache recently filled-up to the > low-water mark it immediately jumped from 180 to 185 days, and since > then it's been switching up and down between 178 and 184. In the past > I've seen larger jumps, such as as 30 to 50 days. > > The LRU policy implementation seems to be a queue with accessed > objects sent to the tail and old objects deleted at the head. The > displayed LRU reference age is taken from the "lastref" value of first > unlocked object from the queue head. > > If everything is working as expected, the reference age should be able > to drop instantaneously, but it shouldn't be able to rise faster than 1 > day per day. Hmm, reading that I get a feeling of the memory caching squid does coming into play. If I'm right its just old memory-only objects being shoved into the LRU queue as they become disk objects. Alternatively it could be objects becoming locked/unlocked for some reason. Amos
