Re: Thinking about breaking up the BufMgrLock

Greg Stark <gsstark@mit.edu> writes:
> I recall the clock sweep having
> been recommended in class as having most of the best properties of LRU with
> very low cost in the critical path.

Right.  The "pending move to front" idea that I suggested is basically a
variant of a clock algorithm: it takes two trips through the LRU list
before a page falls off and becomes eligible for replacement.  (It's
even closer to the "second chance" clock algorithm.)

The $64 question with any of these things is how much performance at the
cache-management level are we willing to give up in order to gain
low-level efficiency?  We probably don't want to go very far in that
direction.  But maybe a clock scan will be a good compromise.
        regards, tom lane