[squid-users] Fluctuating LRU reference age

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.

I'm using 2.6.18 with aufs on FreeBSD.
Received on Thu Mar 06 2008 - 15:56:56 MST