Incorrect CPU count

[GPala9]

 Incorrect CPU count triggers a system crashs (director linux OS sees 7 CPUs instead of 8),

We have some questions about the Westmere 2.40GHz E5620 4 core CPU, … a quite old CPU at this point.

On one of our platforms we occasionally see this CPU boot with all four 4 cores enabled, but only 3 out of 4 hyper-threads enabled. The condition can most commonly be cleared by rebooting the system, though not always. 

We understand that BIOS populates the ACPI Table with available CPU thread information and that Intel reference code creates these portions of the ACPI tables. But we can't tell if Intel's code determined that the thread is disabled or if a code bug caused it to be reported as disabled.

Questions:

• Is Intel aware of any issues with regard to core/hyperthread detection on this CPU?
• Would you be able to provide any insight into root cause for this behavior, whether due to code bugs, CPU stepping, or other potential issues?

[Emeth_O_Intel]

Hi GPala9,

Thank you for posting on the Intel Communities.

I was reviewing the information provided and noticed you have been using an Intel® Xeon® Processor E5620 on your system, according to your information you have seen the system occasionally uses fewer Threads or Cores.

I would like to gather more information on about your system and also ask you some probing question to have a better understanding of this scenario:

Firstly, Could you please so kind and tell me when did you start to notice this behavior? Did this behavior start to happen after a specific update you performed or any recent upgrade of the components?

Secondly, How did you monitor the status of the Thread and Cores of your system? Which software are you using? I noticed you have a Linux Operating System installed on your computer. Could you please so kind and provide to me the output of the following command: (# cat /proc/cpuinfo)

Finally, I will request you to provide me more details of your system such as: 

1. Motherboard.
2. Linux Logs. ( /var/log/syslog or /var/log/messages and /var/log/boot.log )

On the other hand, I would like to provide you some troubleshooting steps and try to isolate the issue:

1. Check the BIOS Settings; if it is possible to set the BIOS using the default settings or clean the CMOS Battery. 
2. Try to reseat the processor by taking it off and put it back into the socket (If it is possible to clean the Thermal Paste) Or if you can test the processor on a different system and check the behavior of the cores and threads it will help to double-check the information.

Answers to the questions:

A) We do not have a similar issue related to this processor related to the Cores or Threads.

B) Sure, I will do my best to figure out the root cause of the issue and find the best solution.

Please provide me those details above and as soon as possible I will proceed with the next step.

Regards,

Emeth O.

Intel Customer Support Technician 

Under Contract to Intel Corporation

[Emeth_O_Intel]

HI GPala9,

I would like to know if you have any other questions or if you still need help in this scenario.

If so, please do not hesitate and let me know and we will be more than happy to assist you.

Regards,

Emeth O.

Intel Customer Support Technician 

Under Contract to Intel Corporation

[Emeth_O_Intel]

Hi GPala9,

I was reviewing this thread and I have not noticed any activity on this community post.

If you have any other question please do not hesitate and contact us and we will be more than happy to assist you. Regards, Emeth O.

Intel Customer Support Technician

Under Contract to Intel Corporation