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Use math formulae in HPA task page

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Tim Bannister 2025-02-11 23:29:43 +00:00
parent b18fcfb162
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1 changed files with 11 additions and 7 deletions
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18
content/en/docs/tasks/run-application/horizontal-pod-autoscale.md
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@ -10,6 +10,7 @@ feature:
Scale your application up and down with a simple command, with a UI, or automatically based on CPU usage.
content_type: concept
weight: 90
math: true
---
<!-- overview -->
@ -131,14 +132,17 @@ From the most basic perspective, the HorizontalPodAutoscaler controller
operates on the ratio between desired metric value and current metric
value:
```
desiredReplicas = ceil[currentReplicas * ( currentMetricValue / desiredMetricValue )]
```math
\begin{equation*}
desiredReplicas = \left( currentReplicas \times { currentMetricValue \over desiredMetricValue } \right)
\end{equation*}
```
For example, if the current metric value is `200m`, and the desired value
is `100m`, the number of replicas will be doubled, since `200.0 / 100.0 ==
2.0` If the current value is instead `50m`, you'll halve the number of
replicas, since `50.0 / 100.0 == 0.5`. The control plane skips any scaling
is `100m`, the number of replicas will be doubled, since
\\( { 200.0 \div 100.0 } = 2.0 \\).
If the current value is instead `50m`, you'll halve the number of
replicas, since \\( { 50.0 \div 100.0 } = 0.5 \\). The control plane skips any scaling
action if the ratio is sufficiently close to 1.0 (within a globally-configurable
tolerance, 0.1 by default).
@ -173,8 +177,8 @@ since it started. This value is configured with the
`--horizontal-pod-autoscaler-cpu-initialization-period` flag, and its
default is 5 minutes.
The `currentMetricValue / desiredMetricValue` base scale ratio is then
calculated using the remaining pods not set aside or discarded from above.
The \\( currentMetricValue \over desiredMetricValue \\) base scale ratio is then
calculated, using the remaining pods not set aside or discarded from above.
If there were any missing metrics, the control plane recomputes the average more
conservatively, assuming those pods were consuming 100% of the desired