[Issue 6038] New: core.cpuid reports unexpected values for threadsPerCPU and hyperThreading

d-bugmail at puremagic.com d-bugmail at puremagic.com
Thu May 19 13:09:07 PDT 2011


http://d.puremagic.com/issues/show_bug.cgi?id=6038

           Summary: core.cpuid reports unexpected values for threadsPerCPU
                    and hyperThreading
           Product: D
           Version: D2
          Platform: Other
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: druntime
        AssignedTo: nobody at puremagic.com
        ReportedBy: kai at redstar.de


--- Comment #0 from kai at redstar.de 2011-05-19 13:04:57 PDT ---
Expectations: From issue 4462 I got the definitions:

coresPerCPU = number of logical cores in a (physical) CPU
threadsPerCPU = number of hyperthreads in each core (name is misleading)

My Core i7 Q820 has 4 physical cores in the CPU and each core can handle 2
hyperthreads. From core.cpuid, I get the following results:

threadsPerCPU = 2
coresPerCPU = 8
hyperThreading = false

I would expect hyperThreading = true in this case.

Contrast this with my Core2 T7600 which is a dualcore CPU with no
hyperthreading. core.cpuid reports:

threadsPerCPU = 2
coresPerCPU = 2
hyperThreading = false

I would expect threadsPerCPU = 1 in this case.

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