| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Vladimir Sitnikov <sitnikov(dot)vladimir(at)gmail(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Andrey Borodin <x4mmm(at)yandex-team(dot)ru>, Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Clock with Adaptive Replacement |
| Date: | 2018-05-04 00:16:57 |
| Message-ID: | CAH2-WzmgABvbkLf4j8c1tkGQJH0Gt9ahOTYTSm+BVO-0J+U3ug@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, May 3, 2018 at 12:37 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Wed, May 2, 2018 at 3:06 PM, Vladimir Sitnikov
> <sitnikov(dot)vladimir(at)gmail(dot)com> wrote:
>> Sample output can be seen here:
>> https://github.com/vlsi/pgsqlstat/tree/pgsqlio#pgsqlio
>
> Neat. Not sure what generated this trace, but note this part:
>
> 3271838881374 88205 0 0 1663 16385 16604 0
> 3271840973321 4368 0 0 1663 16385 16604 1
> 3271842680626 4502 0 0 1663 16385 16604 1
> 3271846077927 4173 0 0 1663 16385 16604 1
>
> If we want to avoid artificial inflation of usage counts, that kind of
> thing would be a good place to start -- obviously 4 consecutive
> accesses to the same buffer by the same backend doesn't justify a
> separate usage count bump each time.
I don't have time to check this out just now, but it seems like an
excellent idea. It would be nice if it could be enhanced further, so
you get some idea of what the blocks are without having to decode them
yourself using tools like pageinspect.
--
Peter Geoghegan
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