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ibulu
Paper Tape
Posts: 5
Registered: ‎03-24-2016
Location: US
Views: 3,324
Message 1 of 15

How to disable CPU Hyperthreading on T460S?

I recently purchased a T460S and would like to disable CPU hyperthreading. I couldn't find any settings in the BIOS related to hyperthreading. Is there anyway to disable it?

 

Thanks

Community SeniorMod
Community SeniorMod
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Message 2 of 15

Re: How to disable CPU Hyperthreading on T460S?

Hello and welcome,

 

I don't think it's a BIOS option on these machines.  There is a way to control this at the OS level, but I can't tell if it sets numer of cores, or number of hyperthreads.  FWIW:

 

https://support.lenovo.com/us/en/documents/ht070947

 

The document refers to Windows 7 but it's there in Win 10 on my T450s too.

 

Z.


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ibulu
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Location: US
Views: 3,300
Message 3 of 15

Re: How to disable CPU Hyperthreading on T460S?

I think this is at the processor level. And only allows you to turn of specific cores. It is rather disappointing that this is option is not available in the bios settings. Any ideas why Lenovo has not enabled this option in the bios? I contacted Lenovo support but they were no help.
Lenovo Staff
Lenovo Staff
Posts: 5,549
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Message 4 of 15

Re: How to disable CPU Hyperthreading on T460S?

Can you please tell me why you need to disable it?

ibulu
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Message 5 of 15

Re: How to disable CPU Hyperthreading on T460S?

I do a lot of scientific computing and most of the programs that I use benefit greatly from single core performance. But, regardless, I believe, as a customer, I should be able to turn on or off hyper-threading depending on my needs.
Lenovo Staff
Lenovo Staff
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Message 6 of 15

Re: How to disable CPU Hyperthreading on T460S?

The feature was removed due to lack of use-cases, and a desire to remove obselete settings/options which do not benefit anyone.  This is why I asked to understand what you are trying to do.

If single-core performance is what you want, I believe there are other ways to accomplish this.

ibulu
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Message 7 of 15

Re: How to disable CPU Hyperthreading on T460S?

Sorry, but that's totally wrong reason to remove this setting. A lot of people that I know off in scientific community will disable hyper-threading right away.

 

I'd love to hear what your suggestions are on achieving optimal single core perfomance without disabling hyper-threading! Because that sounds like magic dust to me!

onix
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Location: California
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Message 8 of 15

Re: How to disable CPU Hyperthreading on T460S?

I am curious, what software do you use where it runs better on a single-core?

ibulu
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Message 9 of 15

Re: How to disable CPU Hyperthreading on T460S?

it is not a questionf of single core vs. multiple cores. But rather multiple physical cores vs. multiple logical cores. This is an important distinction. There are many instances where, as a user, I prefer multiple physical cores instead of multiple logical cores. I'll refer you to one of the discussions on matlab website http://www.mathworks.com/matlabcentral/answers/80129-definitive-answer-for-hyperthreading-and-the-pa...

onix
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Message 10 of 15

Re: How to disable CPU Hyperthreading on T460S?

Earlier you said, "I do a lot of scientific computing and most of the programs that I use benefit greatly from single core performance."  It was confusing.  I am rather surprised that the overhead of hyperthreading is causing a significant performance drop... but to each his own.

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