[Beowulf] bizarre scaling behavior on a Nehalem
kus at free.net
Fri Aug 14 16:10:42 PDT 2009
In message from Tom Elken <tom.elken at qlogic.com> (Fri, 14 Aug 2009
>> On Behalf Of Bill Broadley
>> I put DDR3-1333 in the machine, but the bios seems to want to run
>How many dimms per memory channel do you have?
>My understanding (which may be a few months old) is that if you have
>more than one dimm per memory channel, DDR3-1333 dimms will run at
>i.e. on your 1-CPU system, if you have 6 dimms, you have 2 per memory
>> I'm not sure exactly what speed they are running at.
>Your results look excellent, so I wouldn't be surprised if they are
>running at 1333.
I have 12-18 GB/s on 4 threads of stream/ifort w/DDR3-1066 on dual
E5520 server. But it works under "numa-bad" kernel w/o control of
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