[draft] skip root level check for job enqueue

[mtian29]

What type of PR is this?

#4679

apply same idea to checkHierarchicalQueue can fix #4684 too

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

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Welcome @mtian29!

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[gemini-code-assist]

Summary of Changes

Hello @mtian29, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request refines the job enqueueing process within the scheduler's capacity plugin by introducing an exception for the root queue. Instead of performing a capacity check at the root level, jobs are now allowed to enqueue directly, with the expectation that resource allocation and potential preemption will be handled by the reclaim mechanism. This change aims to streamline the initial placement of jobs and prevent unnecessary blocking at the top-level queue.

Highlights

• Job Enqueue Logic: Modified the checkJobEnqueueableHierarchically function to introduce a special handling for the root queue during job enqueue capacity checks.
• Root Queue Capacity Check Bypass: Jobs will now bypass the capacity check when being enqueued to the root queue, allowing them to proceed and rely on the reclaim mechanism (preemption) to manage resource contention.
• Logging Improvement: Added a klog informational message (V(4)) to indicate when the capacity check for the root queue is skipped for a job.

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[gemini-code-assist]

Code Review

This pull request introduces a change to the capacity plugin to skip capacity checks for the root queue during job enqueueing, allowing reclaim to handle preemption. The review focuses on the correctness and potential implications of this change.

[gemini-code-assist]

This change skips the capacity check for the root queue. While this might be intended to allow reclaim to handle preemption, it's crucial to ensure that this doesn't lead to over-commitment of resources at the root level, potentially starving other queues or causing unexpected behavior. It would be helpful to add more logging to track when and why this condition is being triggered, and to monitor the resource usage of the root queue more closely.

Consider adding a metric to track how often this condition is met, to ensure that it is not happening more often than expected.

[gemini-code-assist]

Consider extracting the condition cp.queueOpts[list[i]].name == cp.rootQueue into a well-named variable to improve readability. This will make the code easier to understand at a glance.

Also, consider adding a comment explaining why level 4 logging is used here.

currentQueueName := cp.queueOpts[list[i]].name

// Skip capacity check for root queue - allow enqueue and let reclaim handle preemption
if currentQueueName == cp.rootQueue {
	klog.V(4).Infof("Skip capacity check for root queue, allow job <%s/%s> to enqueue for potential reclaim", job.Namespace, job.Name)
	continue
}