Identification of HTT cores on newer (CPUID leaf 11) Intel processors

Andrew Boyer aboyer at averesystems.com
Wed Sep 14 17:59:06 UTC 2011


When FreeBSD examines the CPU topology using CPUID leaf 11 in topo_probe_0xb(), it never sets hyperthreading_cpus.  At the end of topo_probe_0x4() it sets hyperthreading_cpus = cpu_logical.

Adding that assignment to line 316 of sys/amd64/amd64/mp_machdep.c seems to do the right thing on a system with two quad-core E5620 CPUs.  The APIC IDs that appear when SMT is enabled in the BIOS get marked AP/HT.

Do you agree?

Thanks,
  Andrew

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Andrew Boyer	aboyer at averesystems.com






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