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Eviction proposal transition frequency

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derekwaynecarr 2016-05-06 17:18:56 -04:00
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docs/proposals/kubelet-eviction.md
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@ -155,6 +155,25 @@ The following node conditions are defined that correspond to the specified evict
The `kubelet` will continue to report node status updates at the frequency specified by
`--node-status-update-frequency` which defaults to `10s`.
### Oscillation of node conditions
If a node is oscillating above and below a soft eviction threshold, but not exceeding
its associated grace period, it would cause the corresponding node condition to
constantly oscillate between true and false, and could cause poor scheduling decisions
as a consequence.
To protect against this oscillation, the following flag is defined to control how
long the `kubelet` must wait before transitioning out of a pressure condition.
```
--eviction-pressure-transition-period=5m0s: Duration for which the kubelet has to wait
before transitioning out of an eviction pressure condition.
```
The `kubelet` would ensure that it has not observed an eviction threshold being met
for the specified pressure condition for the period specified before toggling the
condition back to `false`.
## Eviction scenario
Let's assume the operator started the `kubelet` with the following: