Re-enable Hyper Threading (MPS) under XP SP1a after deactivation

[WaseKabbes]

Hello anyone,
okay, Hyper Threading is´nt reasonable for all
application. Mathematica only uses one CPU, so
deactivation makes sense, e.g. So, that´s I did three
month ago. I changed "hardware -> Computer" to ACPI-PC
and deactivated Hyper Threading in Bios. Now, I want to
re-anable Hyper Threading (Bios and Windows), but the
only I can selsct in "hardware -> computer" is ACPI-PC
and Standard PC. Also any *.inf file (acpi.inf, hal.inf,
machine.inf) has no effect. I even tried editing boot.ini
with /HAL /NumProcs /KERNEL, but no chance.
So, now the question.....how can i re-enable
MultiProcessor System to use Hyper Thrading. I read about
a Hot Fix mentioned somewhere in Ressource Centre, but I
did'nt found any HotFix to download.
What about modifying system files/registry to get a
working Multi Processor System back with Hyper Threading?

Thank's a lot for help.....I do not know how to handle
this problem.

Ralf

 

[Nathan McNulty]

OK, here is the deal. Hyperthreading is able to be enabled in the BIOS.
It has nothing to do with ACPI (at least to the best of my knowledge).
There is nothing in Windows that you can do to activate HyperThreading
until you have turned it on in the BIOS. What happens when you enable it
in the BIOS is Windows installs the second CPU upon the first boot with
it enabled and will then ask you to reboot so the OS can make the changes.

Also, be careful when messing around with system files. That is how you
end up with a BSOD or unbootable Windows. Sometimes you can't even get
in and use System Restore, you have to resort to a Repair operation
which may or may not work properly.

http://support.microsoft.com/default.aspx?scid=kb;en-us;810231

Nathan McNulty

 

[NoNoBadDog!]

Are you aware that enabling HT will result in a general 5 to 10 percent
decrease in speed with most software? Unless you are using HT aware apps,
it is best to leave HT turned off.

Bobby

 

[Alles Kabbes]

Hello Nathan,
exact! And that´s the problem. See your submitted Link (
http://support.microsoft.com/default.aspx?scid=kb;en-
us;810231 ). It says that you only have to enable HT in
Bios. Well, I did. But XP did'nt change to
MultiProcessorSystem as described in article. XP leaves
ACPI-PC, saying ONE PROCESSOR. Under "Hardware ->
Processors" two Processors are listed, but in "Task
Manager -> Performance" or "Hardware -> Computer" only
one Processor is shown. And that´s I need... the Changing
from SingleProcessorSystem to MultiProcessorSystem. XP
does not do what it has to do in fact.
Intel describes that - for right HT functionality - a MPS
under "Hardware -> Computer" and two Processors
under "Task Manager -> Performance" have to be shown.

Any Ideas to wile XP?

Ralf

 

[WaseKabbes]

Okay, I asked MS how to solve the Problem.
Only Possibility to reactivate MPS for HT is a Repair
Installation. Problem.....all Updates and Program
Settings will be overwritten.
At this Point I think I have to let HT disabled.
If anyone knows any tricks/hints to wile XP (registry,
boot.ini) I would be glad to read it here.

Thanks,

Ralf

 

[Name withheld by request]

After you get it fixed, turn it back on, and go to the toms hardware
website, and download his free utility "Task assignment manager"
which allows you to select which apps you DON'T want hypertreading
to run in. It works just like the ctrl-alt-del and unchecking the
affinity, but with this little app running, you don't have to do it
everytime you run the app you don't want "cpu1" ro run in.