2 out of 4 CPUs used in win7, 0 and 1, or 2 and 3, or??

I've got an odd setup and an odd puzzle. I've looked a bunch of places online and haven't found the answer, or a way I might be able to find the answer.

I have a quad Opteron CPU box (8 cores total), with 30gb of mem (for now), and I want to put the fast memory on the CPU sockets that are seen by windows 7, and the slower stuff on the 2 sockets that are not seen by windows 7. How can I see what 2 CPU's are being used by win7 (out of the 4)?



I can boot into server R2 to get all the CPU goodness, but at some point I know that some software will not want to run on R2, but will be ok with win7. Its a pity I can't find the reg setting for realcpulimit, and bump that from 2 to 4.


I know that win7 ultimate can only see 2 physical CPUs/sockets, and I can live with that, the question in my mind is, where to go from here to figure out what 2 sockets/CPUs win7 is using?


Thanks.

charles3 said:

I know that win7 ultimate can only see 2 physical CPUs/sockets, and I can live with that, the question in my mind is, where to go from here to figure out what 2 sockets/CPUs win7 is using?

Is that?
Here is mine, got win 7 ultimate 64 bit. (
AMD Phenom II X4 940 Black Edition)

charles3 said:

How can I see what 2 CPU's are being used by win7 (out of the 4)?

It's the ones which are warm to the touch

That answer is not as insane as it sounds. Any multi-processor Opteron machine is a NUMA playground. Because of the "cache coherency" controllers built into the processors themselves, with Opterons you automagically get "cache coherent NUMA" (ccNUMA) for free.

In short, the combination of NUMA-aware OS and NUMA hardware will attempt to utilise "near" (local node) memory first, and only resort to "far" memory (local to other processors) if necessary. If that does happen, the Opteron CC controllers synchronise the processors' "views" of the cache data.

Your question gets my vote for "best of the month", but I think what you're really asking is "How can I ensure that the fast(er) memory is local/near to the processors/nodes which are going to be used by Win7?"

Since Win7 would never be able to tell you something along the lines of "I'm using the two procs on the upper-left of the mobo", any numerical representation wouldn't be very helpful because it's hard to match it to the physical processor sockets on a given motherboard layout. For example, if I told you that Win7 will limit itself to the first two processor packages detected by the HAL, it would be somewhat tricky to map that to physical layout - is "first" up or down on your mobo?

Hence the suggestion to (gently) touch the processor heatsinks after an hour or so of heavy duty number crunching. The active ones will be the warm ones, and hopefully the motherboard layout or the BIOS will then permit you to work out which slots to populate with the fastest RAM.

I was running the CPUs at max, and the total wattage used by the system went up by almost 200w (measured at the plug), and the lower 2 CPUs felt warmer than the upper ones(see pic), so I am %99.9 sure that win7 uses the lower ones (socket 0 and 1, cores 0-3), but I wanted an additional data point. Oh well, perhaps ill bump into a smart microsoft programmer, and they will know for sure, until then i'm happy with assuming that win7 will take socket 0 and 1, then ignore the others.


Now on to other things...(to be posted in the proper spots)


1) can win7 boot off of a 8.5t EXfat/fat64 TFAT drive array?
2) What issues will I run into with a dual boot Using Windows 7 and Windows Server 2008 R2 ?
3) Any issues running over 100gb of memory (i'm at 60gb and I'm seeing some quirks)

thanks