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I have a Kernel compilation related issue where after successfull compilation and reboot HyperThreading option is lost. I am trying to update my Cent OS 7 vanilla kernel with PREEMPT RT kernel.

This is my first trial or experiment with Kernel.

The default kernel has version :- 3.10.0-123.el7.x86_64 Replacing it with :- 3.10.103-rt114

while in the image below on default kernel I can see HT enabled using i7z tool and lscpu says Nodes 2 and cores = 16

Default Kernel

but on RT Kernel HT is off lscpu says shows Node 1 and core 8.

RT Kernel

Please help I want RT to run with HT and one more help is required. I have compiled the RT kernel many time and thus there are many emtries as "Old ". Help me removing these too.

Shailendra kumar
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  • Both links point to the **same image**. `I have compiled the RT kernel ` - Have you enabled HT when **configured** the kernel? – Tsyvarev Oct 05 '16 at 12:42
  • Sorry for the mistake. Images updated. By RT Kernel I mean to have downloaded and used patch for the kernel as said in this [link](https://www.osadl.org/fileadmin/dam/interface/docbook/howtos/kernel-rt.pdf) – Shailendra kumar Oct 05 '16 at 16:14
  • After patching, you should configure RT kernel (see 2.2.3 until `make` and `make modules_install install`). Check value of option `SCHED_SMT` in the file `.config`. – Tsyvarev Oct 05 '16 at 17:29
  • The CONFIG_SCHED_SMT is set to "y" – Shailendra kumar Oct 06 '16 at 11:50
  • @Tsyvarev please help i really need the solution. If you require I can send you the complete .config detail. I am doing this for first time and am unable to get any update on the topic from google. – Shailendra kumar Oct 08 '16 at 06:33
  • It looks like kernel fails to autodetect that CPU supports HT. I don't know why. Probably, someone else who will visit the question may help. – Tsyvarev Oct 08 '16 at 17:58

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