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Can all the CPUs see all the memory on a blade??

chuckk281
Trusted Contributor

Can all the CPUs see all the memory on a blade??

Ivan had a question from a customer:

 

I got a quick question from a customer that I’m hoping someone can provide clarification.

 

With the new Intel Nehalem architecture, we understand that on a two socket server (ie. BL490c G6) there are 18 DIMM sockets; with 9 DIMMs per processor socket.  Additionally, in order for access to all 18 DIMMs, both processors need to be installed.

 

Based on a fully populated processor and memory configuration (ie. 2 x E5540 processors, and 18 x 4GB DIMMs (72GB)) the question is:

 

 

-          If Processor #1 gets a transaction request, can it utilize memory from all 18 DIMMs or just the 9 x DIMMs associated to it's socket?

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Charles provided the answer:

All cores, All processors, see all the memory. Accessing a neighbor's memory adds some latency, but this may be negligeable depending on apps.

 

Chuck

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Have you used all DIMMs for a single CPU? Have you evaluated what the performance hit is? Let us know.