Message-ID: <455FFD02.1060503@modgraph-usa.com>
Date: Sat, 18 Nov 2006 22:43:14 -0800
From: "Craig A. James" <cjames@modgraph-usa.com>
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To: Richard Troy <rtroy@ScienceTools.com>
CC: Tom Lane <tgl@sss.pgh.pa.us>, Richard Huxton <dev@archonet.com>,
	Russell Smith <mr-russ@pws.com.au>, pgsql-performance@postgresql.org
Subject: Re: Postgres server crash
References: <Pine.LNX.4.33.0611181713170.19262-100000@denzel.in>
In-Reply-To: <Pine.LNX.4.33.0611181713170.19262-100000@denzel.in>
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Richard Troy wrote:
> I did that - spent about two f-ing hours looking for what I wanted. (Guess
> I entered poor choices for my searches. -frown- ) There are a LOT of
> articles that TALK ABOUT OOM, but prescious few actually tell you what you
> can do about it.
> 
> Trying to save you some time:
> 
> On linux you can use the sysctl utility to muck with vm.overcommit_memory;
> You can disable the "feature."
> 
> Google _that_ for more info!


Here's something I found googling for "memory overcommitment"+linux

  http://archives.neohapsis.com/archives/postfix/2000-04/0512.html

  From /usr/src/linux/Documentation/sysctl/vm.txt

  "overcommit_memory:

  This value contains a flag that enables memory overcommitment.
  When this flag is 0, the kernel checks before each malloc()
  to see if there's enough memory left. If the flag is nonzero,
  the system pretends there's always enough memory."

  This flag is settable in /proc/sys/vm

Lo and behold, here it is on my system:

   $ cat /proc/sys/vm/overcommit_memory
   0
   $ cat /proc/sys/vm/overcommit_ratio 
   50

Craig