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Date:      Tue, 16 Nov 2004 12:11:21 +1030
From:      "Wilkinson, Alex" <alex.wilkinson@dsto.defence.gov.au>
To:        freebsd-current@freebsd.org
Subject:   Re: Re: Detection of HTT
Message-ID:  <20041116014121.GJ56252@squash.dsto.defence.gov.au>
In-Reply-To: <20041115043907.GI51636@squash.dsto.defence.gov.au>
References:  <20041115043907.GI51636@squash.dsto.defence.gov.au>

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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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