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Ilya_Z_
Beginner
78 Views

Detecting CPU topology

Hi,
I not sure is this is right place to ask questions like this, but i'll try.
I'm writing a code which enumerate cpu topology. I'm not sure do I fully understood Intel 64 Architecture Processor Topology Enumeration manual.
The x2APIC ID is divide into three bitfields(Package, core, logical procesor IDs). According to this manual to obtain this three sub IDs I must do as follows

SMT_Mask_Width = CPUID.(EAX=11, ECX=0):EAX[4:0] if CPUID.(EAX=11, ECX=0):ECX[15:8] is 1
SMT_Select_Mask = ~((-1) << SMT_Mask_Width )
SMT_ID = x2APIC_ID & SMT_Select_Mask

CorePlus_Mask_Width = CPUID.(EAX=11,ECX=1):EAX[4:0] if CPUID.(EAX=11, ECX=1):ECX[15:8] is 2
CoreOnly_Select_Mask = (~((-1) << CorePlus_Mask_Width ) ) ^ SMT_Select_Mask.
Core_ID = (x2APIC_ID & CoreOnly_Select_Mask) >> SMT_Mask_Width

Pkg_Select_Mask = (-1) << CorePlus_Mask_Width
Pkg_ID = (x2APIC_ID & Pkg_Select_Mask) >> CorePlus_Mask_Width

Could some explain me why to get CoreOnly_Select_Mask I need to (~((-1) << CorePlus_Mask_Width)) raise to the power of SMT_Select_Mask. I'm not sure is it realy reset SMT_Select_Mask. I think to reset SMT_Select_Mask I would only substract this mask form (~((-1) <<CorePlus_Mask_Width))
Or I did not understand something right? If some could give an example of decomposing of x2APIC ID. Showed how it looks like on a test x2APIC.

sorry for my english.

thanks in advance.

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6 Replies
TimP
Black Belt
78 Views

http://www.open-mpi.org/projects/hwloc/ is an open source application which gets information from the OS for those OS which provide it, and from cpuid otherwise.  Intel has a similar thing but closed source.  These things tend to break on each new CPU introduction.

Ilya_Z_
Beginner
78 Views

Thanks for reply. I'll look at this source, but could someone give an example of decomposing x2APIC.

KEERIYAT__P_
Beginner
78 Views

I would like to know some details about Intel storage applications such as Intel storage manager or matrix storage manager, Which Prevents .exe loader coming on to stage or The entire DVD ROM content is not loaded. When these storage managers are removed, everything smoothly loads, Why?

SergeyKostrov
Valued Contributor II
78 Views

>>I would like to know some details about Intel storage applications such as Intel storage manager or >>matrix storage manager, Which Prevents .exe loader coming on to stage or The entire DVD ROM content is >>not loaded. When these storage managers are removed, everything smoothly loads, Why? I'm very sorry but your questions need to be asked in a different Intel forum related to Intel software products you've mentioned.
Bernard
Black Belt
78 Views

>>>When these storage managers are removed, everything smoothly loads, Why?>>>

Some issue related to driver stack or maybe to IRPs , but this forum is not suitable for your question as it was mentioned by Sergey.

SB17
Beginner
78 Views

Maybe it's not quite that, but " likwid-topology" does this. It is open source and you can look at the code

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