Message-ID: <42ECA410.7020804@aeccom.com>
Date: Sun, 31 Jul 2005 12:12:32 +0200
From: =?ISO-8859-1?Q?Dirk_Lutzeb=E4ck?= <lutzeb@aeccom.com>
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To: "J. Andrew Rogers" <jrogers@neopolitan.com>
Cc: josh@agliodbs.com, pgsql-performance@postgresql.org,
	Sven Geisler <sgeisler@aeccom.com>
Subject: Re: Performance problems on 4/8way Opteron (dualcore) HP
References: <BF0FCFE1.71F%jrogers@neopolitan.com>
In-Reply-To: <BF0FCFE1.71F%jrogers@neopolitan.com>
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Anybody knows if RedHat is already supporting this patch on an 
enterprise version?

Regards,

Dirk


J. Andrew Rogers wrote:
> On 7/29/05 10:46 AM, "Josh Berkus" <josh@agliodbs.com> wrote:
> 
>>>does anybody have expierence with this machine (4x 875 dual core Opteron
>>>CPUs)?
>>
>>Nope.   I suspect that you may be the first person to report in on
>>dual-cores.  There may be special compile issues with dual-cores that
>>we've not yet encountered.
> 
> 
> 
> There was recently a discussion of similar types of problems on a couple of
> the supercomputing lists, regarding surprisingly substandard performance
> from large dual-core opteron installations.
> 
> The problem as I remember it boiled down to the Linux kernel handling
> memory/process management very badly on large dual core systems --
> pathological NUMA behavior.  However, this problem has apparently been fixed
> in Linux v2.6.12+, and using the more recent kernel on large dual core
> systems generated *massive* performance improvements on these systems for
> the individuals with this issue.  Using the patched kernel, one gets the
> performance most people were expecting.
> 
> The v2.6.12+ kernels are a bit new, but they contain a very important
> performance patch for systems like the one above.  It would definitely be
> worth testing if possible.
> 
> 
> J. Andrew Rogers
> 
>