topic Re: Finding out disabled cores in Mobile and Desktop Processors

Finding out disabled cores

aozcan — Wed, 24 Feb 2021 10:11:50 GMT

Hello,

I need to find out which cores are disabled on a CPU. How can I do this? I know that reading CAPID6 register is one of the ways, but I am not sure about how to get it done. Is there any system calls or tricks that I need to be aware of?

Thanks

Re: Finding out disabled cores

DeividA_Intel — Thu, 25 Feb 2021 00:58:51 GMT

Hello Aozcan,

Thank you for posting on the Intel® communities.

I am going to list, with steps, the ways that you can see the cores and threads that are working on your system:

1. Task manager.

-Task manager>performance>CPU>right click on the graph>change graph to>logical processor.

2. BIOS.

-The way to find it may be different between brands (MSI, AsRock, Asus), or if it is a laptop, try to contact the motherboard/laptop manufacturer to find the right steps.

Then, you can compare the information displayed with the specifications of your processor. If there is a core that is not showing or is disabled, you can try this:

-Windows key+R>msconfig>Boot tab>advanced options>check on processor> choose the disabled one>OK tap.

If you have any question or need further assistance, do not hesitate to let me know

Regards,

Deivid A.

Intel Customer Support Technician

Re: Finding out disabled cores

aozcan — Thu, 25 Feb 2021 07:05:58 GMT

Hi Deivid,

Thanks for your reply. Is there any "C/C++" way of doing this. I want to read registers directly. Specifically I want to read CAPID6 register into a buffer, but I am not sure if this is what I should do, and I do not how to read a register on Intel platform.

By the way, I should have mentioned it before: my OS is Ubuntu. I can see if a particular core is offline or online by checking /sys/devices/system/cpu/cpu*/online to see if the file contains 0 or 1 which means offline or online respectively.

And also I checked link below:

https://community.intel.com/t5/Software-Tuning-Performance/Understanding-PCICFG-space-information/td-p/1138820

And I understood John McCalpin's answer, but again, I am looking for a C/C++ way of doing this.

Thanks

Re:Finding out disabled cores

DeividA_Intel — Thu, 25 Feb 2021 23:14:31 GMT

Hello Aozcan,

Thanks for letting me know the operating system that you are using. The steps provided, as you noticed, are meant for Windows and since you have Ubuntu I recommend you post on our Linux community to have or get a better response based on your specifications.

You can use the following link to access the Linux community:

https://community.intel.com/t5/tag/linux/tg-p/tag-id/15

If you need any additional information, please submit a new question as this thread will no longer be monitored

Regards,

Deivid A.

Intel Customer Support Technician