Refactor PredicateFn for allocate and preempt actions #2916

wangyang0616 · 2023-06-15T13:38:59Z

Problem phenomenon:

Related issue: Reclaim is not working with GPUSharingEnable if resource used is volcano.sh/gpu-memory #2739

Submit low-priority jobs to occupy all the GPU resources of the cluster, and submit high-priority jobs to request GPU resources.

Expectation: High-priority jobs trigger preemption and run successfully, while some low-priority jobs are evicted and become pending;
Actual result: The high-priority job does not trigger the preemption action and remains in the pending state;

problem causes:

The scheduling process requires advanced node filtering and then optimization. The corresponding processes in Volcano are predicate and nodeorder, and preemption also needs to go through these two stages. In the predicate stage, each plug-in will be called to implement predicateFn to filter nodes. If a plug-in judges that the node does not meet the scheduling requirements and returns an error, the node will be filtered out.

When vgpu's predicateFn (FilterNode) performs node filtering judgment, it judges the remaining gpu resources of the node. If the remaining resources do not meet the pod scheduling, an error will be reported. This implementation is reasonable for allocate, but in preempt scenarios, judgment The logic of whether a pod can be scheduled to a node is whether the full resources of the node can satisfy pod scheduling, not the remaining resources, which causes this problem.

Extended troubleshooting for similar issues:

In addition to the above-mentioned problems in the vgpu resource, check the implementation of other resources and plug-ins, and find that similar problems exist in many places, for example: the predicate-plugin has an upper limit on the number of pods supported by the filtering node node; it is compatible with kube-scheduler-related Filter functions Filtering logic, node port, pod affinity, node volume, pod topology spread, etc. all have similar problems, and it is necessary to provide a general solution to fix the above problems.

Fix:

Solution 1:

Split the predicate function, and classify the resources that can be preempted and the resources that cannot be preempted. The details are as follows:

The predicateResourceFn function is added, and the logical judgment of dynamically changing (preemptible) resources is unified in the function processing, including: remaining resources of gpu, remaining schedulable pod quantity of node, ports supported by node, volume, pod topology spread, usage, etc.
The original predicateFn function handles node immutable (non-preemptive) resources, such as: taint toleration, node affinity, volume zone, numaaware, etc.
The allocate and backfile phases execute predicateFn and predicateResourceFn, which are unchanged from the original logic
Preempt and reclaim execute predicatFn, and when the node is filtered, it is judged that the node is immutable resource, so the above problem can be solved

The pr corresponding to this program: Split the predicate function to solve the resource filtering problem encountered during preemption #2818

shortcoming:

Splitting the predicate function requires exposing too many filtering functions, the semantic distinction is not clear enough, and it is difficult for development and users to understand and maintain

Solution 2:

Extend the return value type of the predicate and add the Status type, indicating that after the node is filtered, scheduling, preemption is allowed, or preemption is not allowed. The details are as follows:

Add status, the status value is Success, Error, Unschedulable, UnschedulableAndUnresolvable, Wait, Skip, etc. (refer to and be compatible with the processing mode of Filter in kube-scheduler)
Micro-refactor the predicate function in each plug-in, allowing to return Unschedulable when preempted resources are insufficient, and returning UnschedulableAndUnresolvable when preempted resources are not allowed.
allocate and backfill accept nodes whose predicate status is Success, and preempt and reclaim accept nodes whose predicate status is Success and Unschedulable.

This scheme corresponds to pr: Predicate adapts allocate and preempt #2916

advantage:

No need to add a new predicate interface, all filtering logic is completed in one function, and the logic processing is more elegant
Compatible with kube-scheduler plug-in filter capabilities, more convenient to expand

After comprehensive consideration, `Solution 2` is more suitable

william-wang · 2023-06-16T02:26:16Z

pkg/scheduler/actions/allocate/allocate.go

@@ -96,13 +97,22 @@ func (alloc *Action) Execute(ssn *framework.Session) {
 	pendingTasks := map[api.JobID]*util.PriorityQueue{}

 	allNodes := ssn.NodeList
-	predicateFn := func(task *api.TaskInfo, node *api.NodeInfo) error {
+	predicateFn := func(task *api.TaskInfo, node *api.NodeInfo) ([]*api.Status, error) {


@wangyang0616 Whether it is enough to use *api.Status?

The predicate plugin integrates multiple filter plug-ins of kube-scheduler. It is necessary to collect the filtering results of each plug-in and judge on the action side.

At present, it is necessary to return the list list. If there is a more elegant solution in the future, we can use it in optimize.

william-wang · 2023-06-16T02:29:03Z

pkg/scheduler/actions/allocate/allocate.go

-			return api.NewFitError(task, node, reason)
+			return nil, api.NewFitError(task, node, reason)
+		}
+		predicateStatus, err := ssn.PredicateFn(task, node)


It's better to make the action code clear and short.

Thank you for your review， here is mainly the core logic that distinguishes the difference between allocate and preempt. It has been modified using the previous logical architecture.

I will consider it later to see if it can be further optimized.

william-wang · 2023-06-16T08:33:35Z

pkg/scheduler/actions/allocate/allocate.go

+		}
+		for _, status := range predicateStatus {
+			if status != nil && status.Code != api.Success {
+				return nil, api.NewFitError(task, node, status.Reason)


just return the first failure?

william-wang · 2023-06-16T08:34:52Z

pkg/scheduler/actions/allocate/allocate.go

@@ -250,4 +254,32 @@ func (alloc *Action) Execute(ssn *framework.Session) {
 	}
 }

+func prePredicateforAllocate(ssn *framework.Session, task *api.TaskInfo, allNodes []*api.NodeInfo, job *api.JobInfo) error {


The prePredicateforAllolcate is similar with prePredicateforBackfill and prePredicateforReclaim

william-wang · 2023-06-16T08:36:53Z

pkg/scheduler/actions/backfill/backfill.go

@@ -101,4 +96,45 @@ func (backfill *Action) Execute(ssn *framework.Session) {
 	}
 }

+func predicateforBackfill(ssn *framework.Session, task *api.TaskInfo, node *api.NodeInfo, fe *api.FitErrors) error {


Can we consolidate the predicateforBackfill, predicateforReclaim, predicateforAllocate and predicateforPrempt?

william-wang · 2023-06-26T07:48:08Z

@Yikun Would you please have a look at the spark failure?

Yikun · 2023-06-26T08:33:11Z

@Yikun Would you please have a look at the spark failure?

It should be fixed by upgrading spark repo to 3.4, lets see results: #2934

william-wang · 2023-07-12T12:31:29Z

pkg/scheduler/util/predicate_helper.go

@@ -107,3 +107,47 @@ func taskGroupID(task *api.TaskInfo) string {
 func NewPredicateHelper() PredicateHelper {
 	return &predicateHelper{taskPredicateErrorCache: map[string]map[string]error{}}
 }
+
+type PredicateStatus interface {
+	IsContainsUnschedulable() bool


The IsContainsUnschedulable is inconsistent with implementation.

It's supposed to be deleted here, done.

william-wang · 2023-07-12T12:43:12Z

pkg/scheduler/actions/backfill/backfill.go

 							task.Namespace, task.Name, node.Name, err)
 						fe.SetNodeError(node.Name, err)
 						continue
 					}

+					if statusSets.ContainsUnschedulable() || statusSets.ContainsUnschedulableAndUnresolvable() ||
+						statusSets.ContainsErrorSkipOrWait() {
+						err := fmt.Errorf("predicates failed in backfill for task <%s/%s> on node <%s>, status is not success",


please combine line #89 and #90

This is used to generate the errors structure. The log output has been updated.

william-wang · 2023-07-12T12:44:40Z

pkg/scheduler/actions/backfill/backfill.go

+					var statusSets util.StatusSets
+					statusSets, err := ssn.PredicateFn(task, node)
+					if err != nil {
+						klog.V(3).Infof("backfill predicates failed for task <%s/%s> on node <%s>: %v",


please make the log clear for user. for example. change the backfill predicates failed xxx to predicate failed in backfill action xxx

william-wang

/lgtm
/approve

william-wang · 2023-07-13T02:14:50Z

/lgtm

jiangkaihua · 2023-07-13T02:27:55Z

/lgtm

…locate and preempt at the same time Signed-off-by: wangyang <wangyang8126@gmail.com>

…ation of this part of adaptation will be rolled back Signed-off-by: wangyang <wangyang8126@gmail.com>

Signed-off-by: w00568049 <wangyang289@huawei.com>

Signed-off-by: wangyang <wangyang8126@gmail.com>

Signed-off-by: w00568049 <wangyang289@huawei.com>

volcano-sh-bot · 2023-07-13T06:36:18Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: william-wang

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william-wang · 2023-07-13T07:17:56Z

The proboot issue is fixed and need to mark the lgtm again.

william-wang · 2023-07-13T07:18:05Z

/lgtm

volcano-sh-bot requested review from hwdef, Thor-wl and william-wang June 15, 2023 13:39

volcano-sh-bot added the size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. label Jun 15, 2023

wangyang0616 mentioned this pull request Jun 15, 2023

Pods are preferentially scheduled to machines that meet the current session resources #2815

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wangyang0616 force-pushed the feature_predicate_suport_preempt branch 3 times, most recently from f015bec to 39d87b0 Compare June 16, 2023 02:13

william-wang changed the title ~~Predicate adapts allocate and preempt~~ [WIP]Predicate adapts allocate and preempt Jun 16, 2023

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wangyang0616 changed the title ~~[WIP]Predicate adapts allocate and preempt~~ Predicate adapts allocate and preempt Jun 16, 2023

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volcano-sh-bot added size/L Denotes a PR that changes 100-499 lines, ignoring generated files. and removed size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. labels Jun 19, 2023

wangyang0616 changed the title ~~Predicate adapts allocate and preempt~~ [WIP]Predicate adapts allocate and preempt Jun 21, 2023

volcano-sh-bot added the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label Jun 21, 2023

wangyang0616 mentioned this pull request Jun 25, 2023

Split the predicate function to solve the resource filtering problem encountered during preemption #2818

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wangyang0616 force-pushed the feature_predicate_suport_preempt branch 2 times, most recently from 94124f7 to 461742b Compare June 27, 2023 14:25

wangyang0616 changed the title ~~[WIP]Predicate adapts allocate and preempt~~ Predicate adapts allocate and preempt Jun 27, 2023

volcano-sh-bot removed the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label Jun 27, 2023

wangyang0616 force-pushed the feature_predicate_suport_preempt branch from 4058273 to 8e060d9 Compare June 29, 2023 08:42

wangyang0616 force-pushed the feature_predicate_suport_preempt branch 3 times, most recently from f1d8522 to 886e438 Compare July 12, 2023 11:06

william-wang reviewed Jul 12, 2023

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wangyang0616 changed the title ~~Predicate adapts allocate and preempt~~ Refactor PredicateFn for allocate and preempt actions Jul 12, 2023

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wangyang0616 and others added 6 commits July 13, 2023 14:35

Transform the predicate interface to support the outer judgment of al…

7bee28e

…locate and preempt at the same time Signed-off-by: wangyang <wangyang8126@gmail.com>

prePredicate does not affect the preemption function, and the modific…

24ad50e

…ation of this part of adaptation will be rolled back Signed-off-by: wangyang <wangyang8126@gmail.com>

Abstract predicate state judgment logic to reduce duplication of code

17eeca5

Signed-off-by: w00568049 <wangyang289@huawei.com>

Resolve the cyclic dependency problem between framework and util

1d22455

Signed-off-by: w00568049 <wangyang289@huawei.com>

Abstract the definition and member method of the predicate status

b3ac598

Signed-off-by: wangyang <wangyang8126@gmail.com>

The invalid interface is deleted and the log information is updated

cb8a186

Signed-off-by: w00568049 <wangyang289@huawei.com>

wangyang0616 force-pushed the feature_predicate_suport_preempt branch from 0683e75 to cb8a186 Compare July 13, 2023 06:36

volcano-sh-bot added the approved Indicates a PR has been approved by an approver from all required OWNERS files. label Jul 13, 2023

volcano-sh-bot assigned william-wang Jul 13, 2023

volcano-sh-bot added the lgtm Indicates that a PR is ready to be merged. label Jul 13, 2023

volcano-sh-bot merged commit 5302995 into volcano-sh:master Jul 13, 2023

wangyang0616 mentioned this pull request Jul 29, 2023

Request to be an Reviewer of Volcano community volcano-sh/community#41

Closed

This was referenced Aug 13, 2023

failed to be scheduled pod's message increased explosively with large number of nodes #3049

Closed

predicate does not stop if node is not suitable for current pod #3050

Closed

lowang-bh mentioned this pull request Aug 29, 2023

Predicate function retrun value is not compatiable with old plugins #3086

Closed

AshinWu mentioned this pull request Nov 9, 2023

vgpu cannot perform high-priority preemption scheduling #3186

Closed

william-wang added this to the v1.8 milestone Jun 12, 2024

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Refactor PredicateFn for allocate and preempt actions #2916

Refactor PredicateFn for allocate and preempt actions #2916

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Refactor PredicateFn for allocate and preempt actions #2916

Refactor PredicateFn for allocate and preempt actions #2916

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wangyang0616 commented Jun 15, 2023 • edited Loading

Problem phenomenon:

problem causes:

Extended troubleshooting for similar issues:

Fix:

Solution 1:

shortcoming:

Solution 2:

advantage:

After comprehensive consideration, Solution 2 is more suitable

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william-wang commented Jun 26, 2023

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william-wang commented Jul 13, 2023

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wangyang0616 commented Jun 15, 2023 •

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After comprehensive consideration, `Solution 2` is more suitable