Re: [HACKERS] Clock with Adaptive Replacement - Mailing list pgsql-hackers

From Andres Freund
Subject Re: [HACKERS] Clock with Adaptive Replacement
Date
Msg-id 20180430181515.gu7pei6sg6wbkqcq@alap3.anarazel.de
Whole thread Raw
In response to Re: [HACKERS] Clock with Adaptive Replacement  (Andrey Borodin <x4mmm@yandex-team.ru>)
Responses Re: [HACKERS] Clock with Adaptive Replacement  (Andrey Borodin <x4mmm@yandex-team.ru>)
List pgsql-hackers
Hi,

On 2018-04-30 15:39:08 +0500, Andrey Borodin wrote:
> I suspect that performance benefits can be not that big or even
> marginal, if we do not extend comprehensive eviction strategy with
> bgwriter fixes and O_DIRECT.

If so, then the improvements aren't real. Bgwriter doesn't matter for
read-only workloads. O_DIRECT doesn't matter much if shared_buffers are
60+% of OS memory.  And even disregarding that, you can just compute
cache hit ratios to see whether things are improving.

Greetings,

Andres Freund


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