RE: [HACKERS] Possible performance improvement: buffer replacement policy

[Mikheev, Vadim]

> > Tom, did we ever test this?  I think we did and found that 
> > it was the same or worse, right?
> 
> I tried it and didn't see any noticeable improvement on the particular
> test case I was using, so I got discouraged and didn't pursue the idea
> further.  I'd like to come back to it someday, though.

I don't know how much useful could be LRU-2 but with WAL we should try
to reuse undirty free buffers first, not dirty ones, just to postpone
writes as long as we can. (BTW, this is what Oracle does.)
So, we probably should put new free dirty buffer just before first
undirty one in LRU.

Vadim