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Distinguish between Preemption due to reclamation and fair sharing #2411

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merged 6 commits into from
Jul 10, 2024
Merged

Distinguish between Preemption due to reclamation and fair sharing #2411

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27f12e8
Distinguish between Preemption due to reclamation and fair sharing
vladikkuzn Jun 14, 2024
3b0785d
Distinguish between Preemption due to reclamation and fair sharing
vladikkuzn Jun 20, 2024
50768c4
Distinguish between Preemption due to reclamation and fair sharing
vladikkuzn Jul 2, 2024
cad0de8
Distinguish between Preemption due to reclamation and fair sharing
vladikkuzn Jul 9, 2024
7327a1e
Distinguish between Preemption due to reclamation and fair sharing
vladikkuzn Jul 10, 2024
f62b1bb
Distinguish between Preemption due to reclamation and fair sharing
vladikkuzn Jul 10, 2024
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9 changes: 7 additions & 2 deletions pkg/scheduler/logging.go
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,8 @@ import (
"k8s.io/klog/v2"

"sigs.k8s.io/kueue/pkg/cache"
"sigs.k8s.io/kueue/pkg/workload"
"sigs.k8s.io/kueue/pkg/scheduler/preemption"
"sigs.k8s.io/kueue/pkg/util/slices"
)

func logAdmissionAttemptIfVerbose(log logr.Logger, e *entry) {
Expand All @@ -37,7 +38,7 @@ func logAdmissionAttemptIfVerbose(log logr.Logger, e *entry) {
}
if log.V(4).Enabled() {
args = append(args, "nominatedAssignment", e.assignment)
args = append(args, "preempted", workload.References(e.preemptionTargets))
args = append(args, "preempted", getWorkloadReferences(e.preemptionTargets))
}
logV.Info("Workload evaluated for admission", args...)
}
Expand All @@ -47,3 +48,7 @@ func logSnapshotIfVerbose(log logr.Logger, s *cache.Snapshot) {
s.Log(logV)
}
}

func getWorkloadReferences(targets []*preemption.Target) []klog.ObjectRef {
return slices.Map(targets, func(t **preemption.Target) klog.ObjectRef { return klog.KObj((*t).WorkloadInfo.Obj) })
}
132 changes: 87 additions & 45 deletions pkg/scheduler/preemption/preemption.go
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Original file line number Diff line number Diff line change
Expand Up @@ -96,8 +96,13 @@ func candidatesFromCQOrUnderThreshold(candidates []*workload.Info, clusterQueue
return result
}

type Target struct {
WorkloadInfo *workload.Info
Reason string
}

// GetTargets returns the list of workloads that should be evicted in order to make room for wl.
func (p *Preemptor) GetTargets(log logr.Logger, wl workload.Info, assignment flavorassigner.Assignment, snapshot *cache.Snapshot) []*workload.Info {
func (p *Preemptor) GetTargets(log logr.Logger, wl workload.Info, assignment flavorassigner.Assignment, snapshot *cache.Snapshot) []*Target {
resPerFlv := resourcesRequiringPreemption(assignment)
cq := snapshot.ClusterQueues[wl.ClusterQueue]

Expand Down Expand Up @@ -164,35 +169,47 @@ func canBorrowWithinCohort(cq *cache.ClusterQueueSnapshot, wl *kueue.Workload) (
return true, &threshold
}

// In cluster queue preemption reasons
const (
InClusterQueueReason string = "InClusterQueue"
)

// In cohort preemption reasons
const (
InCohortReclamationReason string = "InCohortReclamation"
InCohortFairSharingReason string = "InCohortFairSharing"
InCohortReclaimWhileBorrowingReason string = "InCohortReclaimWhileBorrowing"
)

var HumanReadablePreemptionReasons = map[string]string{
InClusterQueueReason: "prioritization in the ClusterQueue",
InCohortReclamationReason: "reclamation within the cohort",
InCohortFairSharingReason: "fair sharing within the cohort",
InCohortReclaimWhileBorrowingReason: "reclamation within the cohort while borrowing",
}

// IssuePreemptions marks the target workloads as evicted.
func (p *Preemptor) IssuePreemptions(ctx context.Context, preemptor *workload.Info, targets []*workload.Info, cq *cache.ClusterQueueSnapshot) (int, error) {
func (p *Preemptor) IssuePreemptions(ctx context.Context, preemptor *workload.Info, targets []*Target, cq *cache.ClusterQueueSnapshot) (int, error) {
log := ctrl.LoggerFrom(ctx)
errCh := routine.NewErrorChannel()
ctx, cancel := context.WithCancel(ctx)
var successfullyPreempted int64
defer cancel()
workqueue.ParallelizeUntil(ctx, parallelPreemptions, len(targets), func(i int) {
target := targets[i]
if !meta.IsStatusConditionTrue(target.Obj.Status.Conditions, kueue.WorkloadEvicted) {
origin := "ClusterQueue"
reason := "InClusterQueue"
if cq.Name != target.ClusterQueue {
origin = "cohort"
reason = "InCohort"
}

message := fmt.Sprintf("Preempted to accommodate a workload (UID: %s) in the %s", preemptor.Obj.UID, origin)
err := p.applyPreemption(ctx, target.Obj, reason, message)
if !meta.IsStatusConditionTrue(target.WorkloadInfo.Obj.Status.Conditions, kueue.WorkloadEvicted) {
message := fmt.Sprintf("Preempted to accommodate a workload (UID: %s) due to %s", preemptor.Obj.UID, HumanReadablePreemptionReasons[target.Reason])
err := p.applyPreemption(ctx, target.WorkloadInfo.Obj, target.Reason, message)
if err != nil {
errCh.SendErrorWithCancel(err, cancel)
return
}

log.V(3).Info("Preempted", "targetWorkload", klog.KObj(target.Obj), "reason", reason, "message", message)
p.recorder.Eventf(target.Obj, corev1.EventTypeNormal, "Preempted", message)
metrics.ReportEvictedWorkloads(target.ClusterQueue, kueue.WorkloadEvictedByPreemption)
log.V(3).Info("Preempted", "targetWorkload", klog.KObj(target.WorkloadInfo.Obj), "reason", target.Reason, "message", message)
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Can you also please add targetClusterQueue?

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@vladikkuzn

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@vladikkuzn vladikkuzn Jul 11, 2024 •
edited

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Added in #2538
WDYT should I also add preemptor's cluster queue?

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The preemptor's information is already part of the log (it comes from the scheduler.go file, which adds the fields to the contextual log).

p.recorder.Eventf(target.WorkloadInfo.Obj, corev1.EventTypeNormal, "Preempted", message)
metrics.ReportEvictedWorkloads(target.WorkloadInfo.ClusterQueue, kueue.WorkloadEvictedByPreemption)
} else {
log.V(3).Info("Preemption ongoing", "targetWorkload", klog.KObj(target.Obj))
log.V(3).Info("Preemption ongoing", "targetWorkload", klog.KObj(target.WorkloadInfo.Obj))
}
atomic.AddInt64(&successfullyPreempted, 1)
})
Expand All @@ -214,35 +231,45 @@ func (p *Preemptor) applyPreemptionWithSSA(ctx context.Context, w *kueue.Workloa
// Once the Workload fits, the heuristic tries to add Workloads back, in the
// reverse order in which they were removed, while the incoming Workload still
// fits.
func minimalPreemptions(log logr.Logger, wlReq resources.FlavorResourceQuantitiesFlat, cq *cache.ClusterQueueSnapshot, snapshot *cache.Snapshot, resPerFlv resourcesPerFlavor, candidates []*workload.Info, allowBorrowing bool, allowBorrowingBelowPriority *int32) []*workload.Info {
func minimalPreemptions(log logr.Logger, wlReq resources.FlavorResourceQuantitiesFlat, cq *cache.ClusterQueueSnapshot, snapshot *cache.Snapshot, resPerFlv resourcesPerFlavor, candidates []*workload.Info, allowBorrowing bool, allowBorrowingBelowPriority *int32) []*Target {
if logV := log.V(5); logV.Enabled() {
logV.Info("Simulating preemption", "candidates", workload.References(candidates), "resourcesRequiringPreemption", resPerFlv, "allowBorrowing", allowBorrowing, "allowBorrowingBelowPriority", allowBorrowingBelowPriority)
}
// Simulate removing all candidates from the ClusterQueue and cohort.
var targets []*workload.Info
var targets []*Target
fits := false
for _, candWl := range candidates {
candCQ := snapshot.ClusterQueues[candWl.ClusterQueue]
if cq != candCQ && !cqIsBorrowing(candCQ, resPerFlv) {
sameCq := cq == candCQ
reason := InClusterQueueReason
if !sameCq && !cqIsBorrowing(candCQ, resPerFlv) {
continue
}
if cq != candCQ && allowBorrowingBelowPriority != nil && priority.Priority(candWl.Obj) >= *allowBorrowingBelowPriority {
// We set allowBorrowing=false if there is a candidate with priority
// exceeding allowBorrowingBelowPriority added to targets.
//
// We need to be careful mutating allowBorrowing. We rely on the
// fact that once there is a candidate exceeding the priority added
// to targets, then at least one such candidate is present in the
// final set of targets (after the second phase of the function).
//
// This is true, because the candidates are ordered according
// to priorities (from lowest to highest, using candidatesOrdering),
// and the last added target is not removed in the second phase of
// the function.
allowBorrowing = false
if !sameCq {
reason = InCohortReclamationReason
if allowBorrowingBelowPriority != nil && priority.Priority(candWl.Obj) >= *allowBorrowingBelowPriority {
// We set allowBorrowing=false if there is a candidate with priority
// exceeding allowBorrowingBelowPriority added to targets.
//
// We need to be careful mutating allowBorrowing. We rely on the
// fact that once there is a candidate exceeding the priority added
// to targets, then at least one such candidate is present in the
// final set of targets (after the second phase of the function).
//
// This is true, because the candidates are ordered according
// to priorities (from lowest to highest, using candidatesOrdering),
// and the last added target is not removed in the second phase of
// the function.
allowBorrowing = false
} else {
reason = InCohortReclaimWhileBorrowingReason
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There is a bug here.

If allowBorrowingBelowPriority is nil, then the reason should stay as InCohortReclamationReason.

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@alculquicondor alculquicondor Jul 16, 2024 •
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it should be more like

if allowBorrowingBelowPriority != nil {
  if priority.Priority(candWl.Obj) >= *allowBorrowingBelowPriority {
    allowBorrowing = false
  } else {
    reason = InCohortReclaimWhileBorrowingReason
  }
}

}
}
snapshot.RemoveWorkload(candWl)
targets = append(targets, candWl)
targets = append(targets, &Target{
WorkloadInfo: candWl,
Reason: reason,
})
if workloadFits(wlReq, cq, allowBorrowing) {
fits = true
break
Expand All @@ -257,24 +284,24 @@ func minimalPreemptions(log logr.Logger, wlReq resources.FlavorResourceQuantitie
return targets
}

func fillBackWorkloads(targets []*workload.Info, wlReq resources.FlavorResourceQuantitiesFlat, cq *cache.ClusterQueueSnapshot, snapshot *cache.Snapshot, allowBorrowing bool) []*workload.Info {
func fillBackWorkloads(targets []*Target, wlReq resources.FlavorResourceQuantitiesFlat, cq *cache.ClusterQueueSnapshot, snapshot *cache.Snapshot, allowBorrowing bool) []*Target {
// In the reverse order, check if any of the workloads can be added back.
for i := len(targets) - 2; i >= 0; i-- {
snapshot.AddWorkload(targets[i])
snapshot.AddWorkload(targets[i].WorkloadInfo)
if workloadFits(wlReq, cq, allowBorrowing) {
// O(1) deletion: copy the last element into index i and reduce size.
targets[i] = targets[len(targets)-1]
targets = targets[:len(targets)-1]
} else {
snapshot.RemoveWorkload(targets[i])
snapshot.RemoveWorkload(targets[i].WorkloadInfo)
}
}
return targets
}

func restoreSnapshot(snapshot *cache.Snapshot, targets []*workload.Info) {
func restoreSnapshot(snapshot *cache.Snapshot, targets []*Target) {
for _, t := range targets {
snapshot.AddWorkload(t)
snapshot.AddWorkload(t.WorkloadInfo)
}
}

Expand Down Expand Up @@ -309,15 +336,15 @@ func parseStrategies(s []config.PreemptionStrategy) []fsStrategy {
return strategies
}

func (p *Preemptor) fairPreemptions(log logr.Logger, wl *workload.Info, assignment flavorassigner.Assignment, snapshot *cache.Snapshot, resPerFlv resourcesPerFlavor, candidates []*workload.Info, allowBorrowingBelowPriority *int32) []*workload.Info {
func (p *Preemptor) fairPreemptions(log logr.Logger, wl *workload.Info, assignment flavorassigner.Assignment, snapshot *cache.Snapshot, resPerFlv resourcesPerFlavor, candidates []*workload.Info, allowBorrowingBelowPriority *int32) []*Target {
if logV := log.V(5); logV.Enabled() {
logV.Info("Simulating fair preemption", "candidates", workload.References(candidates), "resourcesRequiringPreemption", resPerFlv, "allowBorrowingBelowPriority", allowBorrowingBelowPriority)
}
cqHeap := cqHeapFromCandidates(candidates, false, snapshot)
nominatedCQ := snapshot.ClusterQueues[wl.ClusterQueue]
wlReq := assignment.TotalRequestsFor(wl)
newNominatedShareValue, _ := nominatedCQ.DominantResourceShareWith(wlReq)
var targets []*workload.Info
var targets []*Target
fits := false
var retryCandidates []*workload.Info
for cqHeap.Len() > 0 && !fits {
Expand All @@ -326,7 +353,10 @@ func (p *Preemptor) fairPreemptions(log logr.Logger, wl *workload.Info, assignme
if candCQ.cq == nominatedCQ {
candWl := candCQ.workloads[0]
snapshot.RemoveWorkload(candWl)
targets = append(targets, candWl)
targets = append(targets, &Target{
WorkloadInfo: candWl,
Reason: InClusterQueueReason,
})
if workloadFits(wlReq, nominatedCQ, true) {
fits = true
break
Expand All @@ -343,9 +373,18 @@ func (p *Preemptor) fairPreemptions(log logr.Logger, wl *workload.Info, assignme
for i, candWl := range candCQ.workloads {
belowThreshold := allowBorrowingBelowPriority != nil && priority.Priority(candWl.Obj) < *allowBorrowingBelowPriority
newCandShareVal, _ := candCQ.cq.DominantResourceShareWithout(candWl.FlavorResourceUsage())
if belowThreshold || p.fsStrategies[0](newNominatedShareValue, candCQ.share, newCandShareVal) {
strategy := p.fsStrategies[0](newNominatedShareValue, candCQ.share, newCandShareVal)
if belowThreshold || strategy {
snapshot.RemoveWorkload(candWl)
targets = append(targets, candWl)
reason := InCohortFairSharingReason
if !strategy {
reason = InCohortReclaimWhileBorrowingReason
}

targets = append(targets, &Target{
WorkloadInfo: candWl,
Reason: reason,
})
if workloadFits(wlReq, nominatedCQ, true) {
fits = true
break
Expand Down Expand Up @@ -374,7 +413,10 @@ func (p *Preemptor) fairPreemptions(log logr.Logger, wl *workload.Info, assignme
// The criteria doesn't depend on the preempted workload, so just preempt the first candidate.
candWl := candCQ.workloads[0]
snapshot.RemoveWorkload(candWl)
targets = append(targets, candWl)
targets = append(targets, &Target{
WorkloadInfo: candWl,
Reason: InCohortFairSharingReason,
})
if workloadFits(wlReq, nominatedCQ, true) {
fits = true
}
Expand Down