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Date:      Fri, 30 Nov 2007 15:20:36 +0000
From:      Gavin Atkinson <gavin.atkinson@ury.york.ac.uk>
To:        Jim Pingle <lists@pingle.org>
Cc:        freebsd-stable@freebsd.org, Pete French <petefrench@ticketswitch.com>
Subject:   Re: Also seeing 2 x quad-core system slower that 2 x dual core
Message-ID:  <1196436036.20314.12.camel@buffy.york.ac.uk>
In-Reply-To: <475021CE.1000708@pingle.org>
References:  <E1IxvGp-000Mfu-Q7@dilbert.ticketswitch.com> <475021CE.1000708@pingle.org>

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On Fri, 2007-11-30 at 09:44 -0500, Jim Pingle wrote:
> This may be a silly question, but have you tried reducing the RAM on the
> quad core machine to 4GB so the machines match in that respect as well?
> 
> I seem to recall a thread a while back about someone who had slowdowns in a
> certain situation with large amounts of RAM (>4GB).

This was with the Intel 965 chipset, and was fixed with a BIOS upgrade,
something to do with the way the BIOS set cache info up about memory
above 4Gb.  A BIOS upgrade may be worth trying.

Removing memory from the slow one toleave it with 4Gb may be a useful
datapoint.  Note that I don't think you can just set hw.maxmem as that
makes no guarantee as to *whicch* physical 4Gb will get used.

Finally, I assume you are using FreeBSD amd64 and not i386 in PAE mode?
Posting dmesg outputs from both systems somewhere might be useful, I
can't see it in the previous posts.

Gavin



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