Re: mincore() & fincore()

["Cédric Villemain" <cedric@2ndquadrant.com>]

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[sorry, previous mail was sent earlier than expected]

> First, the proposed changes in this email are to be used at least for 
> PostgreSQL extensions, maybe for core.
> 
> Purpose is to offer better monitoring/tracking of the hot/cold areas (and 
> read/write paterns) in the tables and indexes, in PostgreSQL those are by default 
> written in segments of 1GB.
> 
> There are some possible usecase already:
> 
>  * planning of hardware upgrade
>  * easier configuration setup (both PostgreSQL and linux)
>  * provide more informations to the planner/executor of PostgreSQL
> 
> My ideas so far are to 
> 
>  * improve mincore() in linux and add it information like in freeBSD (at 
>    least adding 'mincore_modified' to track clean vs dirty pages).
>  * adding fincore() to make the information easier to grab from PostgreSQL (no 
>    mmap)
>  * maybe some access to those stats in /proc/
> 
> It makes years that libprefetch, mincore() and fincore() are discussed on linux 
> mailling lists. And they got a good feedback... So I hope it is ok to keep on 
> those and provide updated patches.

Johannes, I add you in CC because you're the last one who proposed something. 
Can I update your patch with previous suggestions from reviewers ?

I'm also asking for feedback in this area, others ideas are very welcome.

-- 
Cédric Villemain +33 (0)6 20 30 22 52
http://2ndQuadrant.fr/
PostgreSQL: Support 24x7 - Développement, Expertise et Formation

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