node idle resources not considered in preemption

[mateuszlitwin]

Is this a BUG REPORT or FEATURE REQUEST?:

Uncomment only one, leave it on its own line:

/kind bug

What happened:

There is a pod A (memory: 1GB) running on a node (memory: 2GB), then I scheduled a pod B (memory: 2GB). Pod A was not preempted, because sum of victim resources (1GB) is lower than pod B resource requirements.

What you expected to happen:

Pod A being preempted, because idle resources (1GB) plus victims resources (1GB) is enough to fit pod B (2GB).

How to reproduce it (as minimally and precisely as possible):

Modify TestPreempt in pkg/scheduler/actions/preempt/preempt_test.go.

Anything else we need to know?:

I do not know if it is intentional, but node idle resources are ignored when making preemption decisions. I would expect that we want to check if resources from preempting victims plus node idle resources are enough to fit a preemptor.

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@fejta-bot: Closing this issue.

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