Re: Memory question

From: Josh Berkus <josh(at)agliodbs(dot)com>
To: "Patrick Hatcher" <PHatcher(at)macys(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Memory question
Date: 2003-06-27 19:54:51
Message-ID: 200306271254.51441.josh@agliodbs.com
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Patrick,

> Sorry for posting an obvious Linux question, but have any of you
> encountered this and how have you fixed it.
> I have 6gig Ram box. I've set my shmmax to 3072000000. The database
> starts up fine without any issues. As soon as a query is ran
> or a FTP process to the server is done, the used memory shoots up and
> appears to never be released.

What's you shared_buffers set to after our talk? Do you actually need 3gb of
shmmax?

> My fear is that this may cause problems for my database if this number
> continues to grow. Below is my TOP after running a query, and shutting
> down PgAdmin. While not low now, the amount of free memory has dropped to
> around 11mg. I'll admit I'm not that Linux savvy, but am I reading this
> correct?

No.

> Mem: 6711564K av, 6517776K used, 193788K free, 0K shrd, 25168K

The "used" figure in Top doesn't really tell you anything, since it includes
the kernel buffer which tries to take up all available memory. If you
actually look at the list of processes, I think you'll find that you're only
using 1-2% of memory for applications.

I'm not sure what app would show your "real" free memory.

--
-Josh Berkus
Aglio Database Solutions
San Francisco

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