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I've a issue with am machine I'm running some paralell calculations on. Until now I assumed that core ids need to be sequentially. But on this machine I have: 

lscpu

enter image description here

I get the following Output for:

/bin/cat /proc/cpuinfo | grep 'core id'

enter image description here

Since the code I'm using assumes that the number of cores is equal to max(core ids) + 1, this causes many problems. I can not change this assumption in the code easily. Therefore my questions are the following:

  1. Are the core ids 5-7 just missing?
  2. Or are these cores actually there but not "activated"?
  3. Can I change this in a sense that I can rename the Ids?
  4. Do I have something wrong in a sense that core Ids are never sequentially ordered?
  5. What can cause such a unusual ordering?
Tsyvarev
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HolgerBarlt
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    The Q/A link you have cited is about process IDs, not processor or core IDs, which are completely different, so I've removed the link. – Hadi Brais Feb 20 '19 at 11:33
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    As far as I understand APIC, this standard doesn't require processor cores identifiers to be sequentially allocated. The standard requires only their uniqueness. – Tsyvarev Feb 20 '19 at 13:04
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    This may help: https://unix.stackexchange.com/questions/400605/understanding-core-ids – prl Feb 20 '19 at 14:04
  • Are you running on a VM that doesn't pass through all the physical cores to your guest instance? – Peter Cordes Feb 20 '19 at 18:01
  • As far as I know it is not a VM. I checked with 'sudo virt-what' and got no return value which as far as I know means it is not a VM. – HolgerBarlt Feb 21 '19 at 08:51

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