Re: patch: improve SLRU replacement algorithm

On Wed, Apr 4, 2012 at 1:00 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> , everybody's next few CLOG requests hit some other
> buffer but eventually the long-I/O-in-progress buffer again becomes
> least recently used and the next CLOG eviction causes a second backend
> to begin waiting for that buffer.

This still sounds like evidence that the slru is just too small for
this transaction rate. Otherwise there would be some other buffer that
would be accessed similarly infrequently.

Your fix sounds right to me but I would hope it should be fixing
something that would only happen rarely, not every time theres a
write. It sounds like the slru is thrashing quite a bit more than the
code anticipates.

--
greg