From: | "J(dot) Andrew Rogers" <jrogers(at)neopolitan(dot)com> |
---|---|
To: | <josh(at)agliodbs(dot)com>, <pgsql-performance(at)postgresql(dot)org> |
Cc: | Dirk Lutzeb=?ISO-8859-1?B?5A==?=ck <lutzeb(at)aeccom(dot)com>, Sven Geisler <sgeisler(at)aeccom(dot)com> |
Subject: | Re: Performance problems on 4/8way Opteron (dualcore) |
Date: | 2005-07-29 19:21:53 |
Message-ID: | BF0FCFE1.71F%jrogers@neopolitan.com |
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Lists: | pgsql-performance |
On 7/29/05 10:46 AM, "Josh Berkus" <josh(at)agliodbs(dot)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
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