hyperthreading CPU and broken scheduling?

[Manolis Kiagias]

Wojciech Puchar wrote:
> i have machune with intel's CPU with hyperthreading.
>
> it is detected right, but only first thread is ever used.
>
> top shows at least 50% idle no matter what i run!
>
> what's wrong?
>
>
>     root@:/usr62/src/sys/amd64/compile/serwer.tensor.gdynia.pl
> Timecounter "i8254" frequency 1193182 Hz quality 0
> CPU: Intel(R) Pentium(R) 4 CPU 3.00GHz (3000.13-MHz K8-class CPU)
>   Origin = "GenuineIntel"  Id = 0xf62  Stepping = 2
>
> 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=0xe41d<SSE3,RSVD2,MON,DS_CPL,CNTX-ID,CX16,<b14>,<b15>>
>   AMD Features=0x20100800<SYSCALL,NX,LM>
>   AMD Features2=0x1<LAHF>
>   Logical CPUs per core: 2
> real memory  = 1072562176 (1022 MB)
> avail memory = 1021456384 (974 MB)
> ACPI APIC Table: <PTLTD          APIC  >
> FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
>  cpu0 (BSP): APIC ID:  0
>  cpu1 (AP): APIC ID:  1
> ioapic0 <Version 2.0> irqs 0-23 on motherboard
> acpi0: <PTLTD   RSDT> on motherboard
> acpi0: Power Button (fixed)
> Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000
> acpi_timer0: <24-bit timer at 3.579545MHz> port 0x1008-0x100b on acpi0
> cpu0: <ACPI CPU> on acpi0
> acpi_throttle0: <ACPI CPU Throttling> on cpu0
> cpu1: <ACPI CPU> on acpi0
> acpi_throttle1: <ACPI CPU Throttling> on cpu1
> acpi_throttle1: failed to attach P_CNT
> device_attach: acpi_throttle1 attach returned 6
>
>
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>
To enable hyperthreading, try setting the following in /etc/sysctl.conf:

machdep.hyperthreading_allowed=1

and reboot (or execute sysctl machdep.hyperthreading_allowed=1 by hand).