Re: Configing 8 gig box. - Mailing list pgsql-performance

From Tom Lane
Subject Re: Configing 8 gig box.
Date
Msg-id 29857.1115784636@sss.pgh.pa.us
Whole thread Raw
In response to Re: Configing 8 gig box.  ("Jim C. Nasby" <decibel@decibel.org>)
List pgsql-performance
"Jim C. Nasby" <decibel@decibel.org> writes:
> On Mon, May 09, 2005 at 04:55:53PM -0400, Joel Fradkin wrote:
>> Seems to be only using like 360 meg out of 7 gig free (odd thing is I did
>> see some used swap 4k out of 1.9) with a bunch of users (this may be normal,
>> but it is not going overly fast so thought I would ask).

> This is perfectly normal. Each postgresql backend will only report
> memory usage roughly equal to shared_buffers plus the size of the code
> (16M or so?). If it's in the middle of a sort or vacuum, it will use
> more memory.

One thing to note is that depending on which Unix variant you are using,
top may claim that any particular backend process is using the portion
of shared memory that it's actually physically touched.  This means that
the claimed size of a backend process will grow as it runs (and randomly
needs to touch pages that are in different slots of the shared-memory
buffers) regardless of any actual objective growth in memory needs.

            regards, tom lane

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