Re: [HACKERS] Clock with Adaptive Replacement

02.05.2018 01:37, Peter Geoghegan пишет:
> On Tue, May 1, 2018 at 11:58 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>> I agree that double-counting correlated accesses is a a problem, and I
>> agree that we probably want to do something about it.  I am skeptical
>> that using wall-clock time is the right way to solve that problem
>> because it leads to edge effects
> 
> I agree that wall-clock time is a bad approach, actually. If we were
> to use wall-clock time, we'd only do so because it can be used to
> discriminate against a thing that we actually care about in an
> approximate, indirect way. If there is a more direct way of
> identifying correlated accesses, which I gather that there is, then we
> should probably use it.

I suggest incrementing only once in 1/32 replacements in shared_buffers.
I.e. if size of shared_buffers is 1024, and this page were put into
shared_buffers as 21200, then next time its usage count will be
incremented only after 21232 page were put into shared buffers. And
second time only after 21264 page.

regards,
Yura.