Bug 2186213

This bug was initially created as a copy of Bug #2184860

I am copying this bug because: 



Description of problem:

The node labeller marks the nodes with: 
* their exact TSC frequency
* the lowest TSC frequency in the cluster IF they support tsc-scalable

Hypothetical example, on a cluster where the lowest frequency is X

NAME   TSC-FREQUENCY  TSC-SCALABLE  TSC-FREQUENCY-X  TSC-FREQUENCY-Y
node1  X              true          true              
node2  Y              true          true             true
node3  Y              false                          true

However, TSC scaling may not be an exact number in many CPU models, leaving some possible variation.

See this, same CPU on 2 different systems (or even same system and 2 reboots), there is a 1 Mhz difference that can show up between reboots or systems with same CPU

[    0.000000] tsc: Fast TSC calibration using PIT
[    0.000000] tsc: Detected 2297.345 MHz processor
[    4.127014] tsc: Refined TSC clocksource calibration: 2297.339 MHz

[    0.000000] tsc: Fast TSC calibration using PIT
[    0.000000] tsc: Detected 2297.449 MHz processor
[    4.063010] tsc: Refined TSC clocksource calibration: 2297.338 MHz

If we do X = 2297.338 
         Y = 2297.339
Then a Windows VM with re-enlightenment will never run on node3, because its missing TSC-FREQUENCY-X label by 1MHZ off.
The logic will consider this an heterogeneous cluster, but its not.

The system should be able to schedule VMs on any of those 3 nodes, regardless of TSC-SCALABLE or not. Because these are essentially the same frequency.
Lower layers accept this variance, BZ1839095

Version-Release number of selected component (if applicable):
4.12.10

How reproducible:
Always

Steps to Reproduce:
1. Use systems with TSC-SCALABLE = false and same CPUs, reboot until different frequencies.

Actual results:
* VMs fail to schedule on nodes with same CPU

Expected results:
* VMs scheduled