Message-ID: <20071210162612.a9y113hzjkookooc@webmail.kwsoft.de>
Date: Mon, 10 Dec 2007 16:26:12 +0100
From: Listaccount <lst_hoe01@kwsoft.de>
To: pgsql-admin@postgresql.org
Subject: Dangerous hint in the PostgreSQL manual
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Hello

I have been trapped by the advice from the manual to use "sysctl -w  
vm.overcommit_memory=2" when using Linux (see 16.4.3. Linux Memory  
Overcommit). This value should only be used when PostgreSQL is the  
only Application running on the machine in question. It should be  
checked against the values "CommitLimit" and "Committed_AS" in  
/proc/meminfo on a longer running system. If "Committed_AS" reaches or  
come close to "CommitLimit" one should not set overcommit_memory=2 (see
http://www.redhat.com/archives/rhl-devel-list/2005-February/msg00738.html). I  
think it should be included in the manual as a warning because with  
this setting the machine in question may get trouble with "fork  
failed" even if the standard system tools report a lot of free memory  
causing confusion to the admins.

Regards

Andreas