CODEWITHSUNDEEP
x86intelcpu-corescpuid
Atak_Snajpera
Atak_Snajpera

Reputation: 629

How to detect P/E-Core in Intel Alder Lake CPU?

Which logical processor belongs to the P-core group and which to E-core group?

My first idea was to just check the base clock for each logical processor and then assume that the lowest base clock belongs to E-core (according to intel specs E-cores always have a noticeable lower base clock than P-core).

I was hoping that checking HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor in the Registry would be enough. Unfortunately ~MHz always contains base clock of P-core.

Upvotes: 7

Views: 5693

Answers (1)

A Fog
A Fog

Reputation: 4608

The CPUID instruction gives information about the core, on which it is executed. It is different for P cores and E cores.

The CPUID on Alder Lake is family 6 model 0x9A for both cores when enabled. The CPUID is changed to family 6 model 0x97 when E cores are disabled and AVX512 is enabled.

CPUID leaf 7 EDX bit 15 indicates a hybrid design.

CPUID leaf 1A EAX bit 24-31 indicates the type of core, according to "Game Dev Guide for Alder Lake Performance Hybrid Architecture", https://www.intel.com/content/www/us/en/developer/articles/guide/alder-lake-developer-guide.html

See my discussion at https://www.agner.org/forum/viewtopic.php?f=1&t=79

Upvotes: 12

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