Detection of HTT
Wilkinson, Alex
alex.wilkinson at dsto.defence.gov.au
Mon Nov 15 17:47:22 PST 2004
Is it possible to find out whether HTT is turned on in the BIOS without having
to reboot ? acpidump(8) ?
It's just that I notice that I have a HTT capable CPU:
CPU: Intel(R) Pentium(R) 4 CPU 2.80GHz (2793.19-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>
And
options SMP
compiled into the kernel,
but lack any message in /var/run/dmesg about HTT being enabled.
- aW
Wilkinson, Alex wrote:
>Why is HTT turned off out of the box ? I thought HTT was meant to be a
>hardware 'performance enhancing' feature.
>
>Why do we disable it ?
>
> - aW
FreeBSD will use HTT if the system has it enabled (usually controlled in
the BIOS) and the kernel is compiled for SMP. There are ways to
manually disable HTT but leave SMP enabled in the OS, but the default is
to use it if the above two requirements are met. However, the OS
scheduler is not HTT-aware, so HTT will give a somewhat mixed
performance.
Scott
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