From: | "Anjan Dave" <adave(at)vantage(dot)com> |
---|---|
To: | "Jeff" <threshar(at)torgo(dot)978(dot)org> |
Cc: | <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: Why is this system swapping? |
Date: | 2005-04-27 18:44:27 |
Message-ID: | 4BAFBB6B9CC46F41B2AD7D9F4BBAF785026FF72A@vt-pe2550-001.vantage.vantage.com |
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Thread: | |
Lists: | pgsql-performance |
Sorry, I didn't attach vmstat, the system does actively swap pages. Not
to the point where it crawls, but for some brief periods the console
becomes a bit unresponsive. I am taking this as a sign to prevent future
problems.
anjan
-----Original Message-----
From: Jeff [mailto:threshar(at)torgo(dot)978(dot)org]
Sent: Wednesday, April 27, 2005 2:30 PM
To: Anjan Dave
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: [PERFORM] Why is this system swapping?
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
linux.
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>
http://www.jefftrout.com/
http://www.stuarthamm.net/
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