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Follow-up to Flavor Fungibility Prefers Fit over NoBorrow #6181

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Merged
k8s-ci-robot merged 3 commits into from
Jul 25, 2025
Merged

Follow-up to Flavor Fungibility Prefers Fit over NoBorrow #6181

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c0981c4
Followup
pajakd Jul 25, 2025
c449ab5
Update pkg/scheduler/preemption/preemption_oracle.go
pajakd Jul 25, 2025
1be6c96
Fix whitespaces
pajakd Jul 25, 2025
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7 changes: 1 addition & 6 deletions pkg/scheduler/flavorassigner/flavorassigner.go
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Original file line number Diff line number Diff line change
Expand Up @@ -327,11 +327,6 @@ const (
fit
)

func preferToAvoidBorrowing(fungiblityConfig kueue.FlavorFungibility) bool {
return (fungiblityConfig.WhenCanBorrow == kueue.TryNextFlavor && fungiblityConfig.WhenCanPreempt == kueue.Preempt) ||
(fungiblityConfig.WhenCanBorrow == kueue.TryNextFlavor && fungiblityConfig.WhenCanPreempt == kueue.TryNextFlavor)
}

// isPreferred returns true if mode a is better than b according to the selected policy
func isPreferred(a, b granularMode, fungiblityConfig kueue.FlavorFungibility) bool {
if a.preemptionMode == noFit {
Expand All @@ -349,7 +344,7 @@ func isPreferred(a, b granularMode, fungiblityConfig kueue.FlavorFungibility) bo
}
}

if preferToAvoidBorrowing(fungiblityConfig) {
if fungiblityConfig.WhenCanBorrow == kueue.TryNextFlavor {
if a.needsBorrowing != b.needsBorrowing {
return !a.needsBorrowing
}
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21 changes: 11 additions & 10 deletions pkg/scheduler/preemption/preemption_oracle.go
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Expand Up @@ -48,18 +48,19 @@ func (p *PreemptionOracle) SimulatePreemption(log logr.Logger, cq *cache.Cluster
workloadUsage: workload.Usage{Quota: resources.FlavorResourceQuantities{fr: quantity}},
})

if len(candidates) > 0 {
workloadsToPreempt := make([]*workload.Info, len(candidates))
for i, c := range candidates {
workloadsToPreempt[i] = c.WorkloadInfo
}
revertRemoval := cq.SimulateWorkloadRemoval(workloadsToPreempt)
defer revertRemoval()
}
borrowAfterPreemptions, _ := classical.FindHeightOfLowestSubtreeThatFits(cq, fr, quantity)
if len(candidates) == 0 {
return preemptioncommon.NoCandidates, borrowAfterPreemptions
borrow, _ := classical.FindHeightOfLowestSubtreeThatFits(cq, fr, quantity)
return preemptioncommon.NoCandidates, borrow
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@pajakd pajakd Jul 25, 2025 •
edited
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It actually matters what value of borrow we return with NoCandidates because it is later used to order entries in scheduling.

There are tests that were failing whenever I was trying to return some fixed value to this actually has to be correctly calculated. For that reason I can't think of any new testcase needed for this.

For example the new unit tests for capacity blocking (capacity blocked when lending clusterqueue not guaranteed to reclaim (ReclaimWithinCohort=Never)).

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@mimowo mimowo Jul 25, 2025

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Awesome, thank you for checking that we had unit tests already.

I like unit tests to be our first line of defense whenever possible (especially for scheduling), cause they are much easier to debug than integration or e2e.

}

workloadsToPreempt := make([]*workload.Info, len(candidates))
for i, c := range candidates {
workloadsToPreempt[i] = c.WorkloadInfo
}
revertRemoval := cq.SimulateWorkloadRemoval(workloadsToPreempt)
borrowAfterPreemptions, _ := classical.FindHeightOfLowestSubtreeThatFits(cq, fr, quantity)
revertRemoval()

for _, candidate := range candidates {
if candidate.WorkloadInfo.ClusterQueue == cq.Name {
return preemptioncommon.Preempt, borrowAfterPreemptions
Expand Down