From: Leonardo Francalanci <m_lists@yahoo.it>
To: sthomas@peak6.com <sthomas@peak6.com>
To: alexandre - aldeia digital <adaldeia@gmail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Adding more memory = hugh cpu load
Date: Mon, 10 Oct 2011 16:14:35 +0100 (BST)
Message-ID: <1318259675.10344.YahooMailNeo@web29011.mail.ird.yahoo.com> (raw)
In-Reply-To: <4E92FB87.1030703@peak6.com>
References: <4E92F294.9010405@gmail.com>
<4E92FB87.1030703@peak6.com>
> That's not entirely surprising. The problem with having lots of memory is...
> that you have lots of memory. The operating system likes to cache, and this
> includes writes. Normally this isn't a problem, but with 48GB of RAM, the
> defaults (for CentOS 5.5 in particular) are to use up to 40% of that to cache
> writes.
I don't understand: don't you want postgresql to issue the fsync calls when
it "makes sense" (and configure them), rather than having the OS decide
when it's best to flush to disk? That is: don't you want all the memory to
be used for caching, unless postgresql says otherwise (calling fsync), instead
of "as soon as 1% of memory is used"?
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To: pgsql-performance@postgresql.org
Cc: m_lists@yahoo.it, sthomas@peak6.com, adaldeia@gmail.com
Subject: Re: Adding more memory = hugh cpu load
In-Reply-To: <1318259675.10344.YahooMailNeo@web29011.mail.ird.yahoo.com>
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