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WIP: Introduce a combined metric for CPU and memory #671

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@tiraboschi tiraboschi commented Aug 29, 2025

Introduce a novel metric combining:

  • CPU utilization
  • CPU PSI pressure
  • Memory utilization
  • Memory PSI pressure

The different dimensions are combined using
a root mean square of positive deviations (WRMSPD).

WRMSPD works well because:

  • It naturally combines multiple dimensions into one metric.
  • It ignores “being under the average” (no penalty for low usage).
  • It penalizes large overshoots disproportionately (quadratic effect).
  • With weights, we can prioritize critical resources (e.g. PSI pressure over utilization)

@openshift-ci openshift-ci bot added the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label Aug 29, 2025
@tiraboschi tiraboschi force-pushed the memory_metrics branch 2 times, most recently from 10f9abc to 47ea31d Compare October 20, 2025 14:47
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openshift-ci bot commented Oct 20, 2025

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: tiraboschi
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@tiraboschi tiraboschi force-pushed the memory_metrics branch 3 times, most recently from ba29917 to a7dd4ad Compare November 11, 2025 16:16
@tiraboschi
Introduce a combined metric for CPU and memory
ccf0c16 
Introduce a novel metric combining:
- CPU utilization
- CPU PSI pressure
- Memory utilization
- Memory PSI pressure

The different dimensions are combined computing
the multidimensional euclidean distance from the ideal point.
Only the positive contributions are taken into account
to avoid penalizing underutilized nodes.

A linear multiplier is applied to
make it consistent with existing thresholds.

The proposed  works well because:
- It naturally combines multiple dimensions into one metric.
- It ignores “being under the average” (no penalty for low usage).

Signed-off-by: Simone Tiraboschi <[email protected]>
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openshift-ci bot commented Nov 11, 2025

@tiraboschi: all tests passed!

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@ingvagabund ingvagabund Awaiting requested review from ingvagabund

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