Mapping of memory addresses to physical modules in Windows XP

Posted by Josef Grahn on Super User See other posts from Super User or by Josef Grahn
Published on 2010-04-21T17:19:27Z Indexed on 2010/04/21 17:24 UTC
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I plan to run 32-bit Windows XP on a workstation with dual processors, based on Intel's Nehalem microarchitecture, and triple channel RAM. Even though XP is limited to 4 GB of RAM, my understanding is that it will function with more than 4 GB installed, but will only expose 4 GB (or slightly less).

My question is: Assuming that 6 GB of RAM is installed in six 1 GB modules, which physical 4 GB will Windows actually map into its address space?

In particular:

Will it use all six 1 GB modules, taking advantage of all memory channels? (My guess is yes, and that the mapping to individual modules within a group happens in hardware.)
Will it map 2 GB of address space to each of the two NUMA nodes (as each processor has it's own memory interface), or will one processor get fast access to 3 GB of RAM, while the other only has 1 GB?

Thanks!

Mapping of memory addresses to physical modules in Windows XP

Posted by Josef Grahn on Stack Overflow See other posts from Stack Overflow or by Josef Grahn
Published on 2010-04-21T11:59:57Z Indexed on 2010/04/21 12:03 UTC
Read the original article Hit count: 434

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windows-xp

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memory

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Nehalem

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triple-channel-ram

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numa

I plan to run 32-bit Windows XP on a workstation with dual processors, based on Intel's Nehalem microarchitecture, and triple channel RAM. Even though XP is limited to 4 GB of RAM, my understanding is that it will function with more than 4 GB installed, but will only expose 4 GB (or slightly less).

My question is: Assuming that 6 GB of RAM is installed in six 1 GB modules, which physical 4 GB will Windows actually map into its address space?

In particular:

Will it use all six 1 GB modules, taking advantage of all memory channels? (My guess is yes, and that the mapping to individual modules within a group happens in hardware.)
Will it map 2 GB of address space to each of the two NUMA nodes (as each processor has it's own memory interface), or will one processor get fast access to 3 GB of RAM, while the other only has 1 GB?

Thanks!

Developer IT