Re: Clock sweep not caching enough B-Tree leaf pages? - Mailing list pgsql-hackers

From Stephen Frost
Subject Re: Clock sweep not caching enough B-Tree leaf pages?
Date
Msg-id 20140417185421.GN2556@tamriel.snowman.net
Whole thread Raw
In response to Re: Clock sweep not caching enough B-Tree leaf pages?  (Andres Freund <andres@2ndquadrant.com>)
List pgsql-hackers
* Andres Freund (andres@2ndquadrant.com) wrote:
> > Note that if we somehow come up with a page replacement algorithm that tends
> > to evict pages that are in the OS cache, we have effectively solved the
> > double buffering problem. When a page is cached in both caches, evicting it
> > from one of them eliminates the double buffering. Granted, you might prefer
> > to evict it from the OS cache instead, and such an algorithm could be bad in
> > other ways. But if a page replacement algorithm happens avoid double
> > buffering, that's a genuine merit for that algorithm.
>
> I don't think it's a good idea to try to synchronize algorithms with the
> OSs. There's so much change about the caching logic in e.g. linux that
> it won't stay effective for very long.

There's also more than one OS...
Thanks,
    Stephen

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