The machdep.hyperthreading_allowed & ULE weirdness in 7.1

Hi Jeff,

I have a single-CPU system with P4 HTT-enabled processor 
(7.1-RELEASE-p3), kernel compiled with SCHED_ULE.

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FreeBSD 7.1-RELEASE-p3 #0: Fri Feb 20 09:53:32 UTC 2009
     root_at_foo.com:/usr/obj/usr/src/sys/SSP-PRODUCTION7
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Intel(R) Pentium(R) 4 CPU 3.00GHz (2992.51-MHz 686-class CPU)
   Origin = "GenuineIntel"  Id = 0xf34  Stepping = 4
 
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=0x441d<SSE3,DTES64,MON,DS_CPL,CNXT-ID,xTPR>
   Logical CPUs per core: 2
real memory  = 3758030848 (3583 MB)
avail memory = 3674083328 (3503 MB)
ACPI APIC Table: <IntelR AWRDACPI>
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
  cpu0 (BSP): APIC ID:  0
  cpu1 (AP): APIC ID:  1
ioapic0: Changing APIC ID to 2
ioapic0 <Version 2.0> irqs 0-23 on motherboard
ioapic1 <Version 2.0> irqs 24-47 on motherboard

machdep.cpu_idle_hlt: 1
machdep.hlt_cpus: 0
machdep.hlt_logical_cpus: 0
machdep.logical_cpus_mask: 2

If I flip machdep.hyperthreading_allowed sysctl, I still can see 
processes scheduled to both logical CPUs, yet, if I check IRQ status in 
the systat -vm, the CPU1 is not getting any timer interrupts, while CPU0 
gets twice the normal amount. I wonder if something is broken - I would 
expect no processes to be scheduled to the CPU1.

machdep.hyperthreading_allowed=1:
   top: http://sobomax.sippysoft.com/~sobomax/ScreenShot458.png
   systat -vm: http://sobomax.sippysoft.com/~sobomax/ScreenShot459.png

machdep.hyperthreading_allowed=0:
   top: http://sobomax.sippysoft.com/~sobomax/ScreenShot460.png
   systat -vm: http://sobomax.sippysoft.com/~sobomax/ScreenShot461.png

Please let me know if any other debug information is needed.

-Maxim