| From: | Wei Weng <wweng(at)kencast(dot)com> | 
|---|---|
| To: | pgsql-performance(at)postgresql(dot)org | 
| Subject: | Re: swapping? | 
| Date: | 2002-11-14 15:53:30 | 
| Message-ID: | 1037289210.1348.4.camel@Monet | 
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| Lists: | pgsql-performance | 
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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