cpu hyperthreading in win xp pro

[Robbo]

I have played around with CPU HT in BIOS.
I disabled CPU Hyperthreading and booted into Win XP as usual. I noticed
that there is only 1 CPU recognized in Device Manager (that's logically OK).

I re-enabled the CPU HT in BIOS and returned to Windows. Now there are 2
CPUs in Device manager, however in the task manager Performance tab I can
see only one graph. When I go to View menu and CPU History I only see 1
option "One graph per CPU" and nothing else. I also found that I cannot set
afinity to processes ...
What could go wrong?

 

[Robbo]

I have played around with CPU HT in BIOS.
I disabled CPU Hyperthreading and booted into Win XP as usual. I noticed
that there is only 1 CPU recognized in Device Manager (that's logically
OK).

I re-enabled the CPU HT in BIOS and returned to Windows. Now there are 2
CPUs in Device manager, however in the task manager Performance tab I can
see only one graph. When I go to View menu and CPU History I only see 1
option "One graph per CPU" and nothing else. I also found that I cannot
set afinity to processes ...
What could go wrong?

There is definitely some issue with the Windows XP system. I checked the
LiveCD with Knoppix and it detects 2 cpu with no problem. Still, XP lists
two CPUs in the device manager, but somehow cannot use them both. The
diagnostic tool Everest shows CPU information with Hyper Threading as
"supported but disabled". It is enabled for sure in the BIOS.

What can I do to fix this problem?

 

[Robbo]

I have played around with CPU HT in BIOS.
I disabled CPU Hyperthreading and booted into Win XP as usual. I noticed
that there is only 1 CPU recognized in Device Manager (that's logically
OK).

I re-enabled the CPU HT in BIOS and returned to Windows. Now there are 2
CPUs in Device manager, however in the task manager Performance tab I can
see only one graph. When I go to View menu and CPU History I only see 1
option "One graph per CPU" and nothing else. I also found that I cannot
set afinity to processes ...
What could go wrong?

There is definitely some issue with the Windows XP system. I checked the
LiveCD with Knoppix and it detects 2 cpu with no problem. Still, XP lists
two CPUs in the device manager, but somehow cannot use them both. The
diagnostic tool Everest shows CPU information with Hyper Threading as
"supported but disabled". It is enabled for sure in the BIOS.

What can I do to fix this problem?

 

[Robbo]

I have played around with CPU HT in BIOS.
I disabled CPU Hyperthreading and booted into Win XP as usual. I noticed
that there is only 1 CPU recognized in Device Manager (that's logically
OK).

I re-enabled the CPU HT in BIOS and returned to Windows. Now there are 2
CPUs in Device manager, however in the task manager Performance tab I can
see only one graph. When I go to View menu and CPU History I only see 1
option "One graph per CPU" and nothing else. I also found that I cannot
set afinity to processes ...
What could go wrong?

There is definitely some issue with the Windows XP system. I checked the
LiveCD with Knoppix and it detects 2 cpu with no problem. Still, XP lists
two CPUs in the device manager, but somehow cannot use them both. The
diagnostic tool Everest shows CPU information with Hyper Threading as
"supported but disabled". It is enabled for sure in the BIOS.

What can I do to fix this problem?

 

[Edwin vMierlo]

Actually, you do not need to do anything while you put a second processor
in, or enable hyperthreading
It will be detected/installed as a new hardware via PnP manager.


On Windows XP, the UP (Uni-Processor) APIC HALs recognize the existence of
more than one processor, and report the MP ID. Plug and Play notices that
the
computer devnode's hardware ID list has changed, and moves the devnode back
through the "found new hardware" detection process. Because of this, when
you
add a second processor to a UP APIC computer (either ACPI or non-ACPI) the
MP
files (HAL and kernels) are automatically installed, and you do not have to
manually
update the driver in Device Manager. Because of this, the only time it is
necessary
to manually update the driver in Device Manager to change HALs is for
troubleshooting purposes, or to work around a hardware problem. For example,
some older multi-processor computers do not properly configure the USB
controller interrupt in APIC mode. To resolve this behavior so that USB
works,
you may need to click Update Driver to install the PIC HAL

I seriously suspect your BIOS not enabled, please double check and maybe
post to a hardware group.

For more info on hyperthreading, please see :
http://download.microsoft.com/downl...ae-9272-ff260a9c20e2/Hyper-thread_Windows.doc

HTH,

_Edwin.

 

[Robbo]

Actually, you do not need to do anything while you put a second processor
in, or enable hyperthreading
It will be detected/installed as a new hardware via PnP manager.


On Windows XP, the UP (Uni-Processor) APIC HALs recognize the existence of
more than one processor, and report the MP ID. Plug and Play notices that
the
computer devnode's hardware ID list has changed, and moves the devnode
back
through the "found new hardware" detection process. Because of this, when
you
add a second processor to a UP APIC computer (either ACPI or non-ACPI) the
MP
files (HAL and kernels) are automatically installed, and you do not have
to
manually
update the driver in Device Manager. Because of this, the only time it is
necessary
to manually update the driver in Device Manager to change HALs is for
troubleshooting purposes, or to work around a hardware problem. For
example,
some older multi-processor computers do not properly configure the USB
controller interrupt in APIC mode. To resolve this behavior so that USB
works,
you may need to click Update Driver to install the PIC HAL

I seriously suspect your BIOS not enabled, please double check and maybe
post to a hardware group.

Edwin, I wrote exactly what I did in the BIOS. It was working with HT for 2
years so far until I disabled it, just to check how it works without it. I
booted into Windows and there was only 1 CPU. Then I re-enabled it (it is
now enabled for sure, I checked again 2 times just a moment ago). Now XP Pro
acts weird - device manager lists 2 CPUs, but no options in Task Manager are
available as for multiprocessor system.
I checked with other OS (knoppix) and it shows 2 CPUs working. I definitely
doubt this is a hardware problem.

What I will do is to find some other HDD and install a fresh copy of XP to
absolutely confirm it is a software issue.

 

[Kerry Brown]

Did the HAL change?

 

[Robbo]

How do I check that HAL?

--
rb

Did the HAL change?

 

[Kerry Brown]

In the Device Manager expand Computer. Does it mention multi processor? It's
a long shot but the HAL may have changed when you disabled hyperthreading
and may not have changed back.

 

[Robbo]

In the Device Manager expand Computer. Does it mention multi processor? It's
a long shot but the HAL may have changed when you disabled hyperthreading
and may not have changed back.

No, it does not say "multiprocessor". It says ACPI PC computer (I
translate it to english from my localized Windows version).
Indeed, I remember that before the BIOS changes it mentioned
"multiprocessor machine".

Any suggestion how do I fix that HAL back to multiprocessor machine?

 

[frodo]

Any suggestion how do I fix that HAL back to multiprocessor machine?

the offical way is to run the xp installer again and do a repair install
(not a recovery console! Press ENTER (not R), then it'll find the current
install and offer to Repair it). You'll lose all SP's and updates and
have to reinstall all of them. ugh...

google around, there are sites that will tell you that you can do it
manually. backup before, just in case!!

 

[Kerry Brown]

You may be able to change it in the Device Manager. In the Device Manager
right click Computer and pick Scan for hardware changes. If that doesn't do
it you can try updating the driver. Pick Install from a list, then pick
don't search and see if it lists ACPI Multiprocessor. Be aware that picking
the wrong HAL will cause Windows not to boot. If that happens or none of the
above work you'll have to do a repair install.

http://michaelstevenstech.com/XPrepairinstall.htm

Make sure you have a good backup and a bootable Windows CD of the same
version and service pack level as your installed Windows before you try any
of these fixes.

 

[Robbo]

You may be able to change it in the Device Manager. In the Device Manager
right click Computer and pick Scan for hardware changes. If that doesn't
do it you can try updating the driver. Pick Install from a list, then pick
don't search and see if it lists ACPI Multiprocessor. Be aware that
picking the wrong HAL will cause Windows not to boot. If that happens or
none of the above work you'll have to do a repair install.

I don't know why but it does not list ACPI Multiprocessor. I unchecked "show
only compatible devices" but that did not help.
There are only 2 items:
- standard PC computer
- PC computer with ACPI interface

I am afraid I will need to do a repair install...
Thanks for your support anyway.

 

[Leythos]

I don't know why but it does not list ACPI Multiprocessor. I unchecked "show
only compatible devices" but that did not help.
There are only 2 items:
- standard PC computer
- PC computer with ACPI interface

I am afraid I will need to do a repair install...
Thanks for your support anyway.

http://www.microsoft.com/windowsxp/home/howtobuy/choosing2.mspx

Windows XP Home edition does not support Multiple CPU's - not sure if
you have Home or Prof, but I thought I would mention it.

 

[Robbo]

U¿ytkownik "Leythos" <[email protected]> napisa³ w wiadomo¶ci

http://www.microsoft.com/windowsxp/home/howtobuy/choosing2.mspx

Windows XP Home edition does not support Multiple CPU's - not sure if
you have Home or Prof, but I thought I would mention it.

Thanks for your concern. I have Win XP Pro.
Anyway I heard that Win XP Home supports Hyperthreading (logical multiple
CPUs). It just does not support physical multi CPUs (like the new 2 core
CPUs).

 

[John John]

U¿ytkownik "Leythos" <[email protected]> napisa³ w wiadomo¶ci


http://www.microsoft.com/windowsxp/home/howtobuy/choosing2.mspx

Windows XP Home edition does not support Multiple CPU's - not sure if
you have Home or Prof, but I thought I would mention it.

Thanks for your concern. I have Win XP Pro.
Anyway I heard that Win XP Home supports Hyperthreading (logical
multiple CPUs). It just does not support physical multi CPUs (like the
new 2 core CPUs).

That is not entirely correct. Windows XP Home Edition supports
multi-core processors on single die. Just don't try to get anyone at
Intel or AMD to confirm that, they will tell you to direct your inquiry
to Microsoft, and the information or technical papers concerning Home
Edition and multi-core processors is next to impossible to find at
Microsoft.com. I have yet to see such a paper.

John

 

[Kerry Brown]

That is not entirely correct. Windows XP Home Edition supports
multi-core processors on single die. Just don't try to get anyone at
Intel or AMD to confirm that, they will tell you to direct your
inquiry to Microsoft, and the information or technical papers
concerning Home Edition and multi-core processors is next to
impossible to find at Microsoft.com. I have yet to see such a paper.

John

http://support.microsoft.com/kb/810231

Found with a simple google search

http://www.google.com/search?hl=en&...g+site:microsoft.com&btnG=Google+Search&meta=

 

[Kerry Brown]

I don't know why but it does not list ACPI Multiprocessor. I
unchecked "show only compatible devices" but that did not help.
There are only 2 items:
- standard PC computer
- PC computer with ACPI interface

I am afraid I will need to do a repair install...
Thanks for your support anyway.

It does sound like a repair install will be needed.

 

[John John]

http://support.microsoft.com/kb/810231

Hi Kerry,

I have seen that one before. Hyper-threading is still on a single core
processor. I was refering to true Dual cores, 2 processors on one die.
I know that it works but I can't find a paper from Microsoft that says so.

John