Dual processor, AMD 64 machine freezing.

David O'Brien obrien at freebsd.org
Sun Feb 1 16:49:10 PST 2004

[ Tom, PLEASE don't top-post -- it looses context in follow ups ]

On Sun, Feb 01, 2004 at 06:34:10PM -0500, Haapanen, Tom wrote:
> P.S. For best performance, I think you really want to run 4x 512 MB.
> Running with two DIMMs means either you only get 64-bit memory access (not
> 128-bit) or else you need to put both DIMMs into the CPU1 memory slots
> (which means CPU2 will have to access those through hypertransport).
> From: Mark Sergeant [mailto:msergeant at snsonline.net] 
> 2 x 1GB sticks PC 2700 ECC ram

Tom is very correct -- you want to populate memory in pairs per CPU.
This is so you can use both channels of the DDR memory controller.  If
you only put one DIMM per CPU, you're missing 1/2 your potential
bandwidth.  Consult your motherboard manual to determine which DIMM slots
make up a pairing, not all motherboards are the same.

Also, you want to spread your memory out across all your CPU's to get max
performance.  Look in the freebsd-amd64 archives for where I've detailed
it more.

-- David  (obrien at FreeBSD.org)

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