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Re: Why is this system swapping?

From: Jeff <threshar(at)torgo(dot)978(dot)org>
To: "Anjan Dave" <adave(at)vantage(dot)com>
Cc: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Why is this system swapping?
Date: 2005-04-27 18:29:42
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Apr 27, 2005, at 1:48 PM, Anjan Dave wrote:

> As you can see the system starts utilizing swap at some point, with so 
> many processes. Some time ago we had decided to keep the connections 
> from the pool open for longer

You've shown the system has used swap but not that it is swapping.  
Having swap in use is fine - there is likely plenty of code and whatnot 
that is not being used so it dumped it out to swap. However if you are 
actively moving data to/from swap that is bad. Very bad. Especially on 

To tell if you are swapping you need to watch the output of say, vmstat 
1 and look at the si and so columns.

Linux is very swap happy and likes to swap things for fun and profit.

Jeff Trout <jeff(at)jefftrout(dot)com>

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