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feature(scheduler): simplify QueueingHint by introducing new statuses

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This commit is contained in:
Kensei Nakada
2023-10-19 11:02:11 +00:00
parent de054fbf94
commit cb5dc46edf
17 changed files with 360 additions and 284 deletions
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37
pkg/scheduler/framework/interface.go
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@@ -77,18 +77,30 @@ const (
// Success means that plugin ran correctly and found pod schedulable.
// NOTE: A nil status is also considered as "Success".
Success Code = iota
// Error is used for internal plugin errors, unexpected input, etc.
// Error is one of the failures, used for internal plugin errors, unexpected input, etc.
// Plugin shouldn't return this code for expected failures, like Unschedulable.
// Since it's the unexpected failure, the scheduling queue registers the pod without unschedulable plugins.
// Meaning, the Pod will be requeued to activeQ/backoffQ soon.
Error
// Unschedulable is used when a plugin finds a pod unschedulable. The scheduler might attempt to
// Unschedulable is one of the failures, used when a plugin finds a pod unschedulable.
// If it's returned from PreFilter or Filter, the scheduler might attempt to
// run other postFilter plugins like preemption to get this pod scheduled.
// Use UnschedulableAndUnresolvable to make the scheduler skipping other postFilter plugins.
// The accompanying status message should explain why the pod is unschedulable.
//
// We regard the backoff as a penalty of wasting the scheduling cycle.
// When the scheduling queue requeues Pods, which was rejected with Unschedulable in the last scheduling,
// the Pod goes through backoff.
Unschedulable
// UnschedulableAndUnresolvable is used when a plugin finds a pod unschedulable and
// other postFilter plugins like preemption would not change anything.
// Plugins should return Unschedulable if it is possible that the pod can get scheduled
// after running other postFilter plugins.
// The accompanying status message should explain why the pod is unschedulable.
//
// We regard the backoff as a penalty of wasting the scheduling cycle.
// When the scheduling queue requeues Pods, which was rejected with Unschedulable in the last scheduling,
// the Pod goes through backoff.
UnschedulableAndUnresolvable
// Wait is used when a Permit plugin finds a pod scheduling should wait.
Wait
@@ -97,10 +109,27 @@ const (
// - when a PreFilter plugin returns Skip so that coupled Filter plugin/PreFilterExtensions() will be skipped.
// - when a PreScore plugin returns Skip so that coupled Score plugin will be skipped.
Skip
// Pending means that the scheduling process is finished successfully,
// but the plugin wants to abort the scheduling cycle/binding cycle here.
//
// For example, the DRA plugin sometimes needs to wait for the external device driver
// to provision the resource for the Pod.
// It's different from when to return Unschedulable/UnschedulableAndUnresolvable,
// because in this case, the scheduler decides where the Pod can go successfully,
// but we need to wait for the external component to do something based on that scheduling result.
//
// We regard the backoff as a penalty of wasting the scheduling cycle.
// In the case of returning Pending, we cannot say the scheduling cycle is wasted
// because the scheduling result is used to proceed the Pod's scheduling forward,
// that particular scheduling cycle is failed though.
// So, Pods rejected by such reasons don't need to suffer a penalty (backoff).
// When the scheduling queue requeues Pods, which was rejected with Pending in the last scheduling,
// the Pod goes to activeQ directly ignoring backoff.
Pending
)
// This list should be exactly the same as the codes iota defined above in the same order.
var codes = []string{"Success", "Error", "Unschedulable", "UnschedulableAndUnresolvable", "Wait", "Skip"}
var codes = []string{"Success", "Error", "Unschedulable", "UnschedulableAndUnresolvable", "Wait", "Skip", "Pending"}
func (c Code) String() string {
return codes[c]
@@ -151,7 +180,7 @@ type Status struct {
reasons []string
err error
// failedPlugin is an optional field that records the plugin name a Pod failed by.
// It's set by the framework when code is Error, Unschedulable or UnschedulableAndUnresolvable.
// It's set by the framework when code is Unschedulable or UnschedulableAndUnresolvable.
failedPlugin string
}