Re: configurability of OOM killer

From: Martijn van Oosterhout <kleptog(at)svana(dot)org>
To: Dawid Kuroczko <qnex42(at)gmail(dot)com>
Cc: Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com>, Decibel! <decibel(at)decibel(dot)org>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Jeff Davis <pgsql(at)j-davis(dot)com>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: configurability of OOM killer
Date: 2008-02-07 22:59:32
Message-ID: 20080207225932.GD15660@svana.org
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On Thu, Feb 07, 2008 at 08:22:42PM +0100, Dawid Kuroczko wrote:
> Noooow, I know work_mem is not "total per process limit", but
> rather per sort/hash/etc operation. I know the scheme is a bit
> sketchy, but I think this would allow more memory-greedy
> operations to use memory, while taking in consideration that
> they are not the only ones out there. And that these settings
> would be more like hints than the actual limits.

Given that we don't even control memory usage within a single process
that accuratly, it seems a bit difficult to do it across the board. You
just don't know when you start a query how much memory you're going to
use...

> ....while we are at it -- one feature would be great for 8.4, an
> ability to shange shared buffers size "on the fly". I expect
> it is not trivial, but would help fine-tuning running database.
> I think DBA would need to set maximum shared buffers size
> along the normal setting.

Shared memory segments can't be resized... There's not even a kernel
API to do it.

Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> Those who make peaceful revolution impossible will make violent revolution inevitable.
> -- John F Kennedy

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