Hyperthreading on 9100

Question

My i9100 seems to restrict any one process to 50% of the total processor availability. This results in a processor bound application running for 2 mins 35 secs on i9100 with 2gb as opposed to 55 sec on i8600 with 1gb. Any one know if this really is a restriction and if so how I can remove / change it?

fenderguitarguy · Answer

Try downloading speedswitch xp at http://www.diefer.de/indexe.html and setting the cpu to max speed.

DM5D · Answer

Thanks, but I have done that already and no improvement

Frazell · Answer

What is the application and the rest of your specs? As HyperThreading dosen't = 2x the performance it only means the CPU can use as close to 100% as possible.

accurate81 · Answer

turn off hyper-threading in the BIOS.

Frazell · Answer

@accurate81 wrote: turn off hyper-threading in the BIOS.   There is no reason to disable HT... It would even slow performance of your machine...

accurate81 · Answer

when running processor intensive programs, ie encoding, etc, it can be of benefit to disable hyper threading. xp is throttling the amount of codes/processes allocated to the two virtual processors, these extra processor cycles are being held by windows for a possible second thread. in order to make windows stop "saving" the extra cycles for the non-existent second thread, disable HT in the bios. that should force xp to give all the processor bandwidth/cycles to the program you wish to run.

true, multi-threading capabilities will be diminished, but if you need the extra cycles, it is price you have to pay.

plus you can just turn HT back on if you need simple enough.

DM5D · Answer

Thanks for all your help. I tried turning off hyperthreading which made things marginally worse!

I am beginning to think that something in XP is limiting the amount of processor any one app can use. Will go onto a windows forum and ask there.

accurate81 · Answer

time for me to hunble pie. yum.

Frazell · Answer

@accurate81 wrote:
when running processor intensive programs, ie encoding, etc, it can be of benefit to disable hyper threading. xp is throttling the amount of codes/processes allocated to the two virtual processors, these extra processor cycles are being held by windows for a possible second thread. in order to make windows stop "saving" the extra cycles for the non-existent second thread, disable HT in the bios. that should force xp to give all the processor bandwidth/cycles to the program you wish to run.

true, multi-threading capabilities will be diminished, but if you need the extra cycles, it is price you have to pay.

plus you can just turn HT back on if you need simple enough.

Sorry, but do you know how HT works?

HT Works by showing Windows 2 processors (one logical, one physical) which allows Windows to treat the machine as a dual CPU box. This allows your computer and Dual Processor enabled applications to execute 2 threads at a time instead of one. So putting a very intensive processes on a HT CPU with HT enabled would allow your machine to be more responsive then with HT Disabled or on a non-HT CPU. Simply because the other thread your executing can also be executed instead of having to wait for free CPU time. Intesive Multi-Processor enabled applications like video encoders can be furthur enhanced by HT CPU's because they can get more thru the CPU at one time by leveraging the advantages of running 2 threads instead of one.

I think you should go to http://www.intel.com/personal/products/pentium4/hyperthreading.htm and read the whitepapers on what HyperThreading actually is and what it is not, because you have the wrong view.

Also i don't get what you ment by Windows "saving" cycles... and if that is a true case then how would it affect HT CPU's more so than non-HT CPU's... If you're talking about the System Idle Process then you should know it dosen't do anything by tell the cpu to do nothing when the CPU dosen't have anything to do. Since the CPU has to always be told to do something (it can never be truely idle and still on) this process runs to do that. It runs at the LOWEST priority so it dosen't take CPU time from any running application.

Message Edited by Frazell on 04-14-2005 09:58 AM

Leepee · Answer

Just check that under your running processes there isnt something running at 50% Cpu time.

I had something very simular to what you are discribing and I found that explorer.exe would "ramp" up interms of CPU time and reach 50%.. this caused a noticable drop in machine performs and when manual killed the process things zoom along.

I never did work out why this was happening but it only occured after I had applied the latest MS patch, i rebuilt the system and the issue went away.

mech888 · Answer

i had that problem, i updated bios drivers and problem fixed.

powderoo · Answer

@Frazell wrote:

@accurate81 wrote:
when running processor intensive programs, ie encoding, etc, it can be of benefit to disable hyper threading. xp is throttling the amount of codes/processes allocated to the two virtual processors, these extra processor cycles are being held by windows for a possible second thread. in order to make windows stop "saving" the extra cycles for the non-existent second thread, disable HT in the bios. that should force xp to give all the processor bandwidth/cycles to the program you wish to run.

true, multi-threading capabilities will be diminished, but if you need the extra cycles, it is price you have to pay.

plus you can just turn HT back on if you need simple enough.

Sorry, but do you know how HT works?

HT Works by showing Windows 2 processors (one logical, one physical) which allows Windows to treat the machine as a dual CPU box. This allows your computer and Dual Processor enabled applications to execute 2 threads at a time instead of one. So putting a very intensive processes on a HT CPU with HT enabled would allow your machine to be more responsive then with HT Disabled or on a non-HT CPU. Simply because the other thread your executing can also be executed instead of having to wait for free CPU time. Intesive Multi-Processor enabled applications like video encoders can be furthur enhanced by HT CPU's because they can get more thru the CPU at one time by leveraging the advantages of running 2 threads instead of one.

I think you should go to http://www.intel.com/personal/products/pentium4/hyperthreading.htm and read the whitepapers on what HyperThreading actually is and what it is not, because you have the wrong view.

Also i don't get what you ment by Windows "saving" cycles... and if that is a true case then how would it affect HT CPU's more so than non-HT CPU's... If you're talking about the System Idle Process then you should know it dosen't do anything by tell the cpu to do nothing when the CPU dosen't have anything to do. Since the CPU has to always be told to do something (it can never be truely idle and still on) this process runs to do that. It runs at the LOWEST priority so it dosen't take CPU time from any running application.

Message Edited by Frazell on 04-14-2005 09:58 AM

Is it also true, that in order of HT to be effective that the software must support that technology. Or does software having nothing to do with the process?

Frazell · Answer

The software mainly has to support multiple processors.

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Hyperthreading on 9100

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