Some Intel CPUs have hyper-threading which I can detect by reading bit 28 in register EDX from CPUID. AMD CPUs don't have hyper-threading but some of them have modules which have two integer units and one floating point unit. Is there a way, such as through CPUID, to detect if a CPU has modules?
Edit: based on Jester's answer I have come up with the following untested function (I don't have access to an AMD processor) to determine the number of cores per "compute unit" (aka module).
// input: eax = functionnumber, ecx = 0
// output: eax = output[0], ebx = output[1], ecx = output[2], edx = output[3]
//static inline void cpuid (int output[4], int functionnumber)
void coresPerComputeUnit() {
int abcd[4];
int cores = 1;
cpuid(abcd,0x80000000);
if(abcd[0]<0x8000001E) return; // Fn8000_001E not available
cpuid(abcd,0x8000001E);
cores += (abcd[1] & 0xff00) >> 8; //ebx bit 15:8 CoresPerComputeUnit
}
http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/42301_15h_Mod_00h-0Fh_BKDG1.pdf
You can use cpuid Fn8000_001E Compute Unit Identifiers.
Bits 15:8 of EBX
(ie. BH
) holds CoresPerComputeUnit: cores per compute unit. Value: Product-specific. The number of cores per compute unit is CoresPerComputeUnit+1.
See the AMD Bios and Kernel Developer's Guide.
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