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Re: linux, memory (mis)accounting/reporting, and the planner/optimizer

From: "M(dot) Edward (Ed) Borasky" <znmeb(at)cesmail(dot)net>
To: Greg Smith <gsmith(at)gregsmith(dot)com>
Cc: Dave Youatt <dave(at)fyreball(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: linux, memory (mis)accounting/reporting, and the planner/optimizer
Date: 2009-01-22 06:23:45
Message-ID: 497810F1.5050309@cesmail.net (view raw or flat)
Thread:
Lists: pgsql-performance
Greg Smith wrote:
> On Wed, 21 Jan 2009, Dave Youatt wrote:
> 
>> Does it just accept the configuration parameters provided (e.g. --
>> shared_buffers, effective_cache_size, etc.)?
> 
> That's it.  The only time PostgreSQL gets a report from the OS related
> to memory is if it makes an allocation attempt that fails.  Couldn't
> care less what Linux thinks the rest of the time--unless the OOM killer
> goes on a rampage, counts shared memory badly, and decides to kill a
> database process that is.
> 
> -- 
> * Greg Smith gsmith(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD
> 

The shared memory accounting in Linux got better in the 2.6.25 kernel,
although I'm not sure the user space tools are fully deployed even today
to track it. And of course, lots of servers still use kernels older than
2.6.25.

Re the OOM killer -- maybe a patch to the kernel could make things
"better"??

-- 
M. Edward (Ed) Borasky

I've never met a happy clam. In fact, most of them were pretty steamed.

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