Re: swapping? - Mailing list pgsql-performance

Usually vmstat shows page ins.  I also write a paper on this:

    http://techdocs.postgresql.org/redir.php?link=http://www.ca.postgresql.org/docs/momjian/hw_performance/

The techdocs site has other stuff, see "Optimzation" section:

    http://techdocs.postgresql.org/

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Wei Weng wrote:
> How do you notice that if a system started swapping or not?
>
> Thanks
>
> On Thu, 2002-11-14 at 09:37, Shridhar Daithankar wrote:
> > On 14 Nov 2002 at 10:30, Wei Weng wrote:
> >
> > > The term had been mentioned often enough on this mailing list. Can
> > > someone enlighten me with some description or a URL where I can read on?
> > > And why is it important to postgresql database performace?
> >
> > When programs request more memory than available, OS 'swaps' some memory to
> > special area on disk and make the memory available. To programs, it gives
> > appearance that nearly infinite memory is available.
> >
> > Unfortunately disk are hell slower than RAM and hence swapping slows things
> > down as it takes much to swap in to disk and swap out of disk. Since OS does
> > not care which programs get swapped, it is possible that postgresql instance
> > can get swapped. That slows down effective memory access to knees..
> >
> > That's why for good performance, a serve should never swap..
> >
> > Bye
> >  Shridhar
> >
> > --
> > Peterson's Admonition:    When you think you're going down for the third time --
> > just remember that you may have counted wrong.
> >
> >
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> --
> Wei Weng
> Network Software Engineer
> KenCast Inc.
>
>
>
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