[Beowulf] Nehalem memory configs

Jan Heichler jan.heichler at gmx.net
Wed Apr 8 13:01:59 PDT 2009


Hallo Jeff,

Mittwoch, 8. April 2009, meintest Du:

JL> Peter Kjellstrom wrote:
>> On Wednesday 08 April 2009, Joe Landman wrote:
>>   
>>> As an FYI, Beowulf veteran Jeff Layton wrote up a nice article on memory
>>> configuration issues for Nehalem (I had seen some discussion on this
>>> previously).
>>>     

>> Can anyone confirm that mixing different sizes of dimms, even when keeping to 
>> a by-three-symmetric configuration, actually does degrade performance?

>> That is, first hand information that config 1 will be slower than config 2:

>> 1: two sockets, 3x 1G and 3x 2G per socket RDIMM (total 18G @1066)
>> 2: two sockets, 6x 1G(or 2G) per socket RDIMM (total 12G (or 24G) @1066)

>> /Peter
>>   

JL> I can confirm it because I've got it on a test box I've been running :)

Can you give us the result of a stream-benchmark? with 12 x RDIMM in asymmetric config and 6 x RDIMM ? both running at 1066?

Would be great!

Jan
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