Turn off Hyperthreading

I have heard a number of people here discuss hyperthreading. There was a suggestion to me from tech support for another problem to turn off hyperthreading. I didn't see anything about hypertheading in my BIOS. Is that the only place to look.... is it ever called anything else? (I have WinXP) I am not sure how to look up info about my BIOS to pass it on here.

Thanks in advance

Take Care

ORIGINAL: rjt

I didn't see anything about hypertheading in my BIOS.

Are you sure you have a hyperthreading CPU? Not all P4's ar HT. If you do have a HT CPU, maybe your BIOS version doesn't support it. You can try upgrading your BIOS to the latest version.

What mobo do you have??

Turning HT off in Sonar only won't always solve problems. Sonar lets me record or play audio for about 2 seconds before BSOD'ing on me when I have my Tascam US-122 attached unless I also disable it in the BIOS.

That's my experience as well....that's why I have H/T disablet in BIOS...

You should only turn off Hyperthreading if you do not have a multiprocessor system.

Many MBs share bios setups and have an option for enabling and disabling hyperthreading.

Hyperthreading is a function that will only benefit you if you are using two or more processors.

If you have a single processor and hyperthreading is enabled, then your OS will attempt load balancing for two processors which will actually increase your CPU usage and lower the CPU performance capabilities of your system.

No, it's not true, at least not uncategorically. The first implementations had performance degradations under many conditions. However, BIOS and chipset implementations have improved quite a bit. I run SETI@Home when I'm not otherwise using the computer and my workunit output increases by about 25% with HT enabled. Similarly, encoding MPEG2 video for DVD mastering is about 20% faster for me. Overall system responsiveness under load improves as well. My experiences are not unique. Check out the many detailed reviews on various hardware sites. If your BIOS is HT-aware and your OS, applications and device drivers are, too, then it generally helps performance except under certain circumstances and while running certain applications.

For those of you who are experiencing a better result utilizing HT technology with single processors, follow the stages of application workflow and see why.

If your application has multithreading options turned on and your MB has HT disabled, then the result will be your application sending multithreaded requests to an OS that is not allowing multi-thread processing requests, your operating system is not load balancing for HyperThreading and will ultimately perform worse than if you had the function enabled on your MB because half of your processing requests are being sent in to outer space.

HyperThreading is a function that ONLY occurs on multiple processor systems. Hyper-Threading Technology provides thread-level-parallelism (TLP) on each processor resulting in increased utilization of processor execution resources.

http://www.intel.com/technology/hyperthread/

ORIGINAL: jyoung

Application don't request to have their threads executed.

The application must be coded for multithread functionality.

ORIGINAL: tmrpro

ORIGINAL: jyoung

Application don't request to have their threads executed.

The application must be coded for multithread functionality.

This is true, but every application has at least one thread and that thread is scheduled along with all the other threads (and there can be thousands) on the system by the kernel. An application can boost the priority of its threads, which would make it more likely to get CPU slices, but this is not normally done, plus the thread would need to be running under an account that has the permissions boost thread priority.

I read the article too and I understand this to be GOOD thing. You want the execution resources of the CPU to be utilized. You see, by having extra resources to schedule threads with, the OS and all the processes running on it will be able to do more in a given period of time.

You need to read the part that says multiple threads of software applications can be run simultaneously on one processor and By allowing the processor to use on-die resources that would otherwise have been idle, Hyper-Threading Technology provides a performance boost on multi-threading and multi-tasking operations

The entire OS is multi-threaded. Even though an particular application is not multi-threaded there are still hunderds of other multithreaded operations going on in device drivers, and other system processes, and the quicker they can get their work done the better. So this can only be of benefit to the performance of the system.

Keep in mind that Hyperthreading has been shown to hinder performance in certain instances as well. It's not always a good thing.

-S

Well, I may have completely misunderstood what has been explained to me by people involved in serious CPU development. Hey, if that's the case, I'll be glad to step aside and swallow my foot.

But, It has been explained to me (by the people who developed HT) and it is my understanding that the better results that people see with HyperThreading enabled on single processor machines is due to an application having multithreads active or multitasking creating multiple threads that would otherwise be overlooked by the single processor.

Without HT, the OS splits the threads of a multithread enabled application for load balancing and the processor only receives the first 1/2 of the processing request in the request stream because the application has indicated that there are two processors and Windows only designates one thread per processor unless HyperThreading is enabled, then when the remaining 50% processing request has not been fulfilled it is streamed at the back end of the initial stream. With HT enabled, Windows allows both 50% requests to go to the single processor at the same time, thus the result is 50% faster processing then the previous described process stream load and balance.

But if you take the same application and disable its use of multithreading (optimizing for a single processor) and do not have HyperThreading enabled then the ultimate result will be faster because there is no need for managing the HT in the first place.

The method of using HyperThreading to manage what is improperly set up in your application in the first place is like going around the block to get across the street.

But if it works better for you to leave it enabled and you think its better then leave it enabled.

I think when you run a poll of which method produces the better overall results (not talking about applications that have multitasking enabled) you will find that everyone with single processors is getting better results with HT DISABLED.

If you asked me which way I've gone I'd say "on which workstation"?

It's enabled on my Tyan Tiger MB with dual Opteron 64 bit 244s, but it is disabled on my P4T-E with a single 2G.

The rest of my machines have it disabled and they are all single processor machines. There are a total of 8 workstations in my main facility.

& if you want to take it up with me on a direct level, your more than welcomed to send me a private email here:

http://tmrpro.com/contact.html

it's on in the BIOS (haven't looked in awhile where.) Is there another place?

Hey Code,

It doesn't hurt my feelings if you know more about than I do. Frankly, I'd like to be 100% clear about it myself.

I will say that you are running things on a workstation that we never run (I.E.: internet & anti-virus). We don't introduce any software to our dedicated workstations that interfere with the operation of the specified applications.

Also, in reply to Rousseau:

It is my understanding that Windows has always allowed to MultiTask multiple single threaded processes and does so very successfully without HyperThreading.

Is this not the case?

1 bump for an answer....

Do Windows and non-hyperthreaded CPUs allow to MultiTask multiple single threaded processes without HyperThreading?