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: 2008-02-08 10:35:21
Message-ID: 20080208103521.GA4162@svana.org
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On Fri, Feb 08, 2008 at 09:59:37AM +0100, Dawid Kuroczko wrote:
> That is true. However it is possible to allocate more than one shared memory
> segment. At simplest I would assume that DBA should specify minimum
> shared memory size (say, 1GB) and expected maximum (2GB). And that
> between minimum and maximum SHM should be allocated in reasonably
> sized chunks. Say 128MB chunks. So that DBA could resize shared buffers
> to 1.5GB, decide this was not a good idea after all and reduce it to 1280MB.

I think the biggest problem is that the shared memory segments have to be
mapped to the same address in every process. The chance that can happen
after the server has been running for a while is small. Perhaps if the
postmaster allocated it waited for all the clients to refork...

Would people be OK with an indeterminate delay between changing the
setting and when it takes effect?

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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