Hyperthreading (no doubt again!).

[Astral Fridge Magnet]

Hello,

This has probably been talked about before, so just in case, here we go again.

Is there any "real" advantage in disabling hyperthreading? Things run quite smoothly on my desktop, except B4 doesn't work and Native Instruments suggest I disable Hyperthreading.

Yet very recently I came across the following information on the Steinberg Forums regarding the subject:



"Windows requires the correct HAL (Hardware Abstraction Layer) to properly communicate with the CPU. This HAL is really a small set of .dll's that gets selected during Windows Setup. If HT is on in the BIOS when Setup is invoked...the ACPI MultiProcessor PC (you can view this in Device Manager->Computer and right click on the Device you see there...choose Properties and view the driver files.) .dll is installed and off you go.

However suddenly turning HT off in the BIOS and then re-starting does not properly install the ACPI Uniprocessor PC .dll (despite many who have tried it). It appears to work...but trust me - I have messed with this particular thing for a long time and the only guaranteed way to get the best performance following shutting off HT in the BIOS is to re-install Windows immediatly after HT has been turned off in the BIOS. A reinstall ensures all the system requirements for the uniprocessor HAL are installed correctly and clean from the Windows install CD."



So to my understanding, disabling hyperthreading in the BIOS is not really effective unless you reinstall Windows again.

So, is this really true? For me that would cause quite a hassle as it means reauthorising and applying for new serial numbers for a lot of my software.

Thanks

[garyb]

just do the windows install over the top of the old install(make a disk image first if you can). that way, all of your software will still be in place. i always turn off hyperthreading from the get-go.

[Astral Fridge Magnet]

Thanks for the reply Garyb.

So are you saying that I won't necessarily lose all my installed software (and more importantly my authorisations), if I do an install over the top with hyperthreading disabled in the BIOS. Of course I will make an image first of my setup before I attempt this.

Someone on another forum wrote the following:

Maybe you could try setting B4's affinity to one CPU in Task manager. If that works there is an app called Powerstrip that enables you to set affinity per app (I have HP turned on as I have graphics apps that need it but have affinity set to one CPU for Scope and a couple of other audio apps such as Logic)

The link for powerstrip is:

http://www.entechtaiwan.com/util/index.shtm

Dunno anything about it nor do I really know or understand what it does.

The problem really lies with B4 not working properly with my desktop machine (works fine on my laptop though) and the advice I got was disable hyperthreading from Native Insts support. Otherwise, I am happy enough with the performance of my desktop.

Thanks Garyb for always being so helpful and providing advice here on this forum. What would we do without you?

[Astral Fridge Magnet]

Hello again Garyb,

I came across this on another forum, and seeing you are technically savvy, could I ask your opinion on this:



You Dont need to intsall XP again to disable HT effectively.

You would only need to install XP again IF your current XP
was installed withOut HT already been turned on in the BIOS.
Since you already have HT enabled, then HT was already turned on in the BIOS = No einstall required.

Basically since with HT, its a virtual thing, ie only cpu but a "trick" that the OS has to pick up on.
Windoze XP can only pick up on it only when it is installing BUT only if it is
already enabled in the BIOS & The HAL is enabled within the ACPI.
Kind of forcing XP to recognise this virtual trick.

If Windoze XP has been installed with ACPI HAL enabaled, (which you have)
i.e. Task Manager > Performance shows two cpus
then disabling HT in BIOS is easy & effective, No XP reinstall required.



Then I came across the following on the Microsoft site regarding my question on Hyperthreading:

http://support.microsoft.com/kb/811366

Which seems to contradict the above advice (I think).


Can you shed some light on this please?

Thanks

[garyb]

well, if it works, no worries.

hyperthreading is a marketing tool. with or without it the computer is almost the same, in terms of performance. there is a slight performance hit without it, but it's not substantial. the os sees the "virtual" processors as multiple processors. i'd think that you'd have the wrong HAL if you installed the os with HT on. that said, it might still work just fine(try it!). you can also uninstall the HAL in the device manager and then reinstall it with the install disk. i'd just reinstall over the top of the old install. it'll only take a few minutes.

i really doubt if your other programs will suddenly become non-functional w/o HT, and, if you have a disk image, you really can't break anything. go ahead and try it....

[Astral Fridge Magnet]

Hi,

Well thanks for your reply Garyb. As you say, I suppose all I can do is try it out and see. I'll finish installing everything I need to install, make a backup image so I can revert back to it should things go wrong.

Thanks for your input.

[garyb]

my pleasure.