Re: Pre-allocation of shared memory ... - Mailing list pgsql-hackers

From Jon Lapham
Subject Re: Pre-allocation of shared memory ...
Date
Msg-id 3EE893BE.7080305@extracta.com.br
Whole thread Raw
In response to Re: Pre-allocation of shared memory ...  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tom Lane wrote:> [snip]
> The
> setting now called "paranoid overcommit" is IMHO the *only* acceptable
> one for any sort of server system.  With anything else, you risk having
> critical userspace daemons killed through no fault of their own.

Wow.  Thanks for the info.  I found the documentation you are referring 
to in Documentation/vm/overcommit-accounting (on a stock RH9 machine).

It seems that the overcommit policy is set via the sysctl 
`vm.overcommit_memory'.  So...

[root@bilbo src]# sysctl -a | grep -i overcommit
vm.overcommit_memory = 0

...the default seems to be "Heuristic overcommit handling".  It seems 
that what we want is "vm.overcommit_memory = 3" for paranoid overcommit.

Thanks for getting to the bottom of this Tom.  It *is* insane that the 
default isn't "paranoid overcommit".

-- 
-**-*-*---*-*---*-*---*-----*-*-----*---*-*---*-----*-----*-*-----*--- Jon Lapham  <lapham@extracta.com.br>
Riode Janeiro, Brasil Work: Extracta Moléculas Naturais SA     http://www.extracta.com.br/ Web: http://www.jandr.org/
 
***-*--*----*-------*------------*--------------------*---------------




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