From: Josh Berkus <josh@agliodbs.com>
Reply-To: josh@agliodbs.com
Organization: Aglio Database Solutions
To: pgsql-performance@postgresql.org
Subject: Re: Tuning Effective Cache Question
Date: Wed, 17 Aug 2005 13:31:38 -0700
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Cc: Chris Hoover <revoohc@gmail.com>
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Chris,

> I have a RHEL 2.1 box running with dual Xeon (2.6 GHz I believe and
> they have HT on).  The box has 8GB memory.  In my postgresql.conf, I
> have set the effective_cache_size = 530505 (~4GB).
>
> However, I am noticing on this machine, top is telling me that I have
> ~3.5GB in the buff and only 3GB in cached.

effective_cache_size is just information for the query planner; it does not 
affect the actually system file cache.

-- 
--Josh

Josh Berkus
Aglio Database Solutions
San Francisco