cpuunclaimed.py: CPU samples arrived at skewed offsets

I'm trying to run ```tools/cpuunclaimed.py``` on a machine running Ubuntu 18.04 with a 4.18 kernel. The machine has 2x Xeon E5-2630 (Haswell) dies, 16 cores (32 threads). Turbo Boost, C-states and P-states have all been disabled from the BIOS. Additionally, ```intel_idle.max_cstate``` is set to 0:
```
$ cat /sys/module/intel_idle/parameters/max_cstate
0
$
```

Nevertheless, the script quits anywhere between 1 to 5 seconds:
```
$ sudo ./cpuunclaimed.py
Sampling run queues... Output every 1 seconds. Hit Ctrl-C to end.
%CPU 0.16%, unclaimed idle 5.05%
ERROR: CPU samples arrived at skewed offsets (CPUs may have powered down when idle), spanning 710556 ns (expected < 400400 ns). Debug with -J, and see the man page. As output may begin to be unreliable, exiting.
$ sudo ./cpuunclaimed.py
Sampling run queues... Output every 1 seconds. Hit Ctrl-C to end.
ERROR: CPU samples arrived at skewed offsets (CPUs may have powered down when idle), spanning 722753 ns (expected < 400400 ns). Debug with -J, and see the man page. As output may begin to be unreliable, exiting.
$ sudo ./cpuunclaimed.py
Sampling run queues... Output every 1 seconds. Hit Ctrl-C to end.
%CPU 0.17%, unclaimed idle 5.39%
ERROR: CPU samples arrived at skewed offsets (CPUs may have powered down when idle), spanning 746505 ns (expected < 400400 ns). Debug with -J, and see the man page. As output may begin to be unreliable, exiting.
```

There is hardly any load on the machine (as can be seen). I've tried the same under load, and the behavior is similar.

From what I understand, the CPUs should not be powering down. Is there anything I'm missing?

Start with tools/cpuunclaimed.py and reproduce the skewed-offset error on the reported Ubuntu 18.04 and 4.18 kernel setup. Use the script's -J debugging option and consult its man page; done means identifying the cause of the premature exit and documenting or correcting the behavior without unreliable output.

Written by the indexing model from the issue text.