__cpuid returns incorrect number of logical processors on Xeon X5660

[idata]

Hello,

I have a HP Z800 with a dual Xeon X5660. 2 x 6 cores x Hyperthreading = 24 logical processors.

In Windows 7 x64, calling GetSystemInfo returns 24 logical processors. Calling GetLogicalProcessorInformation also returns 24. (2 processor packages, 24 logical processors, 12 processor cores).

But calling __cpuid returns 32. I also get 32 even if I disabled hyperthreading in the BIOS.

CPU-Z reports the right information. In the task manager, I see 24 cpus.

I am trying to determine the affinity of each core so that I only run 1 thread per core (no collision between 2 logical processors running on the same core).

I have another machine with a dual Xeon E5520 (2 x 4 cores x Hyperthreading = 16 logical processors).

On the Xeon E5520, setting the affinity to 1, 2, 4, 8 will make the thread run on the first 4 cores while setting the affinity 16, 32, 64 and 128 will make the thread run on the next 4 cores.

On the Xeon X5660, setting the affinity from 1 to 32 will make the thread run on the 6 cores while setting the affinity to 64 to 2048 will make the thread run on different logical processors but on the same cores. Performance are much lower in that case.

I compiled a small program that I found on microsoft web http://msdn.microsoft.com/query/dev10.query?appId=Dev10IDEF1&l=EN-US&k=k%28__CPUID%29;k%28DevLang-%22C%2B%2B%22%29;k%28TargetOS-WINDOWS%29&rd=true site that shows an example of __cpuid and __cpuidex.

I made sure that I have the latest version of the BIOS and that all the chipset drivers are up to date according to the Intel Update Tool.

Any suggestions are welcomed and appreciated.

Here's the output that I got from the tool that I compiled:

For InfoType 0CPUInfo[0] = 0xbCPUInfo[1] = 0x756e6547CPUInfo[2] = 0x6c65746eCPUInfo[3] = 0x49656e69

For InfoType 1

CPUInfo[0] = 0x206c1CPUInfo[1] = 0x200800CPUInfo[2] = 0x29ee3ffCPUInfo[3] = 0xbfebfbff

For InfoType 2

CPUInfo[0] = 0x55035a01CPUInfo[1] = 0xf0b2ffCPUInfo[2] = 0x0CPUInfo[3] = 0xca0000

For InfoType 3

CPUInfo[0] = 0x0CPUInfo[1] = 0x0CPUInfo[2] = 0x0CPUInfo[3] = 0x0

For InfoType 4

CPUInfo[0] = 0x3c004121CPUInfo[1] = 0x1c0003fCPUInfo[2] = 0x3fCPUInfo[3] = 0x0

For InfoType 5

CPUInfo[0] = 0x40CPUInfo[1] = 0x40CPUInfo[2] = 0x3CPUInfo[3] = 0x1120

For InfoType 6

CPUInfo[0] = 0x7CPUInfo[1] = 0x2CPUInfo[2] = 0x9CPUInfo[3] = 0x0

For InfoType 7

CPUInfo[0] = 0x0CPUInfo[1] = 0x0CPUInfo[2] = 0x0CPUInfo[3] = 0x0

For InfoType 8

CPUInfo[0] = 0x0CPUInfo[1] = 0x0CPUInfo[2] = 0x0CPUInfo[3] = 0x0

For InfoType 9

CPUInfo[0] = 0x0CPUInfo[1] = 0x0CPUInfo[2] = 0x0CPUInfo[3] = 0x0

For InfoType 10

CPUInfo[0] = 0x7300403CPUInfo[1] = 0x4CPUInfo[2] = 0x0CPUInfo[3] = 0x603

For InfoType 11

CPUInfo[0] = 0x1CPUInfo[1] = 0x2CPUInfo[2] = 0x100CPUInfo[3] = 0x0

For InfoType 80000000

CPUInfo[0] = 0x80000008CPUInfo[1] = 0x0CPUInfo[2] = 0x0CPUInfo[3] = 0x0

For InfoType 80000001

CPUInfo[0] = 0x0CPUInfo[1] = 0x0CPUInfo[2] = 0x1CPUInfo[3] = 0x2c100000

For InfoType 80000002

CPUInfo[0] = 0x65746e49CPUInfo[1] = 0x2952286cCPUInfo[2] = 0x6f655820CPUInfo[3] = 0x2952286e

For InfoType 80000003

CPUInfo[0] = 0x55504320CPUInfo[1] = 0x20202020CPUInfo[2] = 0x20202020CPUInfo[3] = 0x58202020

For InfoType 80000004

CPUInfo[0] = 0x30363635CPUInfo[1] = 0x20402020CPUInfo[2] = 0x30382e32CPUInfo[3] = 0x7a4847

For InfoType 80000005

CPUInfo[0] = 0x0CPUInfo[1] = 0x0CPUInfo[2] = 0x0CPUInfo[3] = 0x0

For InfoType 80000006

CPUInfo[0] = 0x0CPUInfo[1] = 0x0CPUInfo[2] = 0x1006040CPUInfo[3] = 0x0

For InfoType 80000007

CPUInfo[0] = 0x0CPUInfo[1] = 0x0CPUInfo[2] = 0x0CPUInfo[3] = 0x100

For InfoType 80000008

CPUInfo[0] = 0x3028CPUInfo[1] = 0x0CPUInfo[2] = 0x0CPUInfo[3] = 0x0CPU String: GenuineIntelStepping ID = 1Model = 12Family = 6Extended model = 2CLFLUSH cache line size = 64Logical Processor Count = 32

The following features are supported:

SSE3 MONITOR/MWAIT CPL Qualified Debug Store Virtual Machine Extensions Enhanced Intel SpeedStep Technology Thermal Monitor 2 Supplemental Streaming SIMD Extensions 3 L1 Context ID CMPXCHG16B Instruction xTPR Update Control Perf\Debug Capability MSR

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