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Date: Wed, 6 May 2009 02:20:21 -0400
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Subject: HyperThreading
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Hello,

I'm running FreeBSD 7.2-RELEASE on a dual-core Xeon. It has a custom
compiled SMP kernel, ACPI enabled, with the ULE scheduler.

I've been looking into HyperThreading, and I've come to the conclusion
that I should not use it. I've been told that HTT is disabled by
default, however sysctl and dmesg seems to contradict that:

CPU: Intel(R) Xeon(TM) CPU 2.40GHz (2395.93-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0xf29  Stepping = 9
  Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Features2=0x4400<CNXT-ID,xTPR>
  Logical CPUs per core: 2
FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
 cpu0 (BSP): APIC ID:  0
 cpu1 (AP/HT): APIC ID:  1
 cpu2 (AP): APIC ID:  2
 cpu3 (AP/HT): APIC ID:  3
cpu0: <ACPI CPU> on acpi0
cpu1: <ACPI CPU> on acpi0
cpu2: <ACPI CPU> on acpi0
cpu3: <ACPI CPU> on acpi0
SMP: AP CPU #2 Launched!
SMP: AP CPU #3 Launched!
SMP: AP CPU #1 Launched!



machdep.hyperthreading_allowed: 1
hw.ncpu: 4
kern.smp.disabled: 0
kern.smp.active: 1


Am I correct to assume that the above means that HTT is enabled?
There is nothing in my loader.conf, sysctl.conf, or kernel config file
related to hyperthreading.

Thanks.