Hyper threading on a Precision 530 MT

Marc Mondragon Marcmo at RitchieCapital.com
Mon Jun 10 10:06:00 CDT 2002

One more question on this...

Is the BIOS hyperthreading setting availability controlled by CPU ID?

I have some 530's with P4 2.2 GHz processors and a couple with what I thought were P4 1.7 GHz processors.  When I do a cat /proc/cpuinfo one the 1.7 processors it show the acpi and ht flags.  But the BIOS does not give me the option of setting hyperthreading on.  I've upgraded the BIOS version so they are all the same and I've turned acpismp=force on but it does not work.

Any ideas?

Marc Mondragon

-----Original Message-----
From: Matt_Domsch at Dell.com [mailto:Matt_Domsch at Dell.com]
Sent: Thursday, June 06, 2002 4:33 PM
To: Marc Mondragon
Cc: linux-poweredge at dell.com
Subject: RE: Hyper threading on a Precision 530 MT

> Is hyper threading not supposed to work on the workstation's?

It's fairly easy to see if the CPU itself supports hyperthreading.  If so,
/proc/cpuinfo lists the set of flags for each processor, and included in
that list will be "ht".  The 2.4.9-21 and above kernels will certainly show
this if available.  Since you've got the 2.2GHz Xeon CPUs, I believe they

Then the BIOS needs to enable HT.  On many systems, it's default is off.
After power-on, go into BIOS Setup to enable HT.  That would certainly
explain what you're seeing.

Then, you already know about the acpismp=force trick to make the kernel
recognize it for those that don't do it automatically.

If that doesn't work, come on back and we'll try some more.


Matt Domsch
Sr. Software Engineer
Dell Linux Solutions www.dell.com/linux
Dell internal Linux lists @ http://insidelists.us.dell.com
Dell public Linux lists @ http://lists.us.dell.com
#1 US Linux Server provider for 2001 and Q1/2002! (IDC May 2002)

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