Message-ID: <47600274.40009@commandprompt.com>
Date: Wed, 12 Dec 2007 07:47:00 -0800
From: "Joshua D. Drake" <jd@commandprompt.com>
Organization: Command Prompt, Inc.
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To: mlunnon@rwa-net.co.uk
CC: Sven Geisler <sgeisler@aeccom.com>, pgsql-performance@postgresql.org
Subject: Re: Limited performance on multi core server
References: <475FB50B.8060701@rwa-net.co.uk> <475FCF1E.7030608@aeccom.com>
	<475FED09.2030102@rwa-net.co.uk>
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Matthew Lunnon wrote:
> Hi Sven,
> 
> Does this mean that one option I have is to use a multi core Intel based 
> server instead of an AMD based server?

Wow... hold on.

>> I remember that I also an issue with AMD Opterons before Pg 8.1
>> There is a specific Opteron behaviour on shared memory locks which adds
>> a extra "penalty" during the execution time for Pg code before 8.1.

I would like to see some proof of this.


>> I can you provide my patch for Pg 8.0 which should be adaptable for Pg
>> 7.4 if you can compile PostgreSQL.
>>

The real answer here is to upgrade to 8.1.10 or 8.2.5. 64bit if you can.

>>> I have a 4 * dual core 64bit AMD OPTERON server with 16G of RAM, running
>>> postgres 7.4.3.  This has been recompiled on the server for 64 stored
>>> procedure parameters, (I assume this makes postgres 64 bit but are not

This type of machine, assuming you have decent IO available will 
generally be very fast with anything >= 8.1.

>>> changes to postgresql.sql:
>>>
>>> max_connections = 500
>>> shared_buffers = 96000

Way to high for 7.4. Way to low for 8.1 or above (based on what you 
mention your work load is)

>>> sort_mem = 10240

Based on your specs this actually may be fine but I would suggest 
reviewing it after you upgrade.

>>> effective_cache_size = 1000000
>>>

Again, too low for 8.1 or above.

Sincerely,

Joshua D. Drake

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