enhancemanet: reduce calculation calls

[lowang-bh]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

1. function is called when need, reduce calling times of function GetPodStartTime() or PodPriority();
2. reuse the result of former function calling;

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

benchmark test result

go version go1.20.1
goos: darwin
goarch: arm64
pkg: k8s.io/kubernetes/pkg/scheduler/util

before:

Benchmark10kPods-8   	   67680	     16837 ns/op	       0 B/op	       0 allocs/op
Benchmark10kPods-8   	   69393	     16928 ns/op	       0 B/op	       0 allocs/op
Benchmark10kPods-8   	   68298	     16942 ns/op	       0 B/op	       0 allocs/op
Benchmark10kPods-8   	   70198	     16125 ns/op	       0 B/op	       0 allocs/op

Benchmark100kPods-8   	    2661	    444173 ns/op	       0 B/op	       0 allocs/op
Benchmark100kPods-8   	    2674	    446439 ns/op	       0 B/op	       0 allocs/op
Benchmark100kPods-8   	    2715	    454089 ns/op	       0 B/op	       0 allocs/op
Benchmark100kPods-8   	    2665	    440868 ns/op	       0 B/op	       0 allocs/op
Benchmark100kPods-8   	    2646	    452669 ns/op	       0 B/op	       0 allocs/op

after:

Benchmark10kPods-8   	   80383	     14392 ns/op	       0 B/op	       0 allocs/op
Benchmark10kPods-8   	   81895	     14073 ns/op	       0 B/op	       0 allocs/op
Benchmark10kPods-8   	   78211	     14602 ns/op	       0 B/op	       0 allocs/op
Benchmark10kPods-8   	   76614	     15110 ns/op	       0 B/op	       0 allocs/op

Benchmark100kPods-8   	    2736	    409138 ns/op	       0 B/op	       0 allocs/op
Benchmark100kPods-8   	    2932	    414789 ns/op	       0 B/op	       0 allocs/op
Benchmark100kPods-8   	    2908	    403114 ns/op	       0 B/op	       0 allocs/op
Benchmark100kPods-8   	    2925	    394417 ns/op	       0 B/op	       0 allocs/op
Benchmark100kPods-8   	    2958	    410171 ns/op	       0 B/op	       0 allocs/op

benchmark code

func Benchmark10kPods(b *testing.B) {
	num := 10000
	now := time.Now()
	pods := make([]*v1.Pod, 0, num)
	for i := 0; i < num; i++ {
		prio := rand.Int31n(int32(num))
		rndTime := now.Add(time.Second * time.Duration(rand.Int63n(int64(num))))
		pods = append(pods, newPriorityPodWithStartTime("pod"+strconv.Itoa(i), prio, rndTime))
	}

	victims := &extenderv1.Victims{Pods: pods}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		GetEarliestPodStartTime(victims)
	}
	b.StopTimer()
}

Does this PR introduce a user-facing change?

None

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[k8s-ci-robot]

Hi @lowang-bh. Thanks for your PR.

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[lowang-bh]

/sig scheduling

[sanposhiho]

/ok-to-test

[sanposhiho]

/release-note-none

[sanposhiho]

/release-note-none

[sanposhiho]

@lowang-bh
Sorry, I've just realized this change is the same as #117208 which was submitted a bit earlier than this.

[lowang-bh]

@lowang-bh Sorry, I've just realized this change is the same as #117208 which was submitted a bit earlier than this.

Yeah, I see. I find my pr has less function calls than that one.
And, I take a benchmark on that modify, here is the result.

Benchmark10kPods-8   	   52952	     22429 ns/op	       0 B/op	       0 allocs/op
Benchmark10kPods-8   	   47960	     24871 ns/op	       0 B/op	       0 allocs/op
Benchmark100kPods-8   	    1060	   1126838 ns/op	       0 B/op	       0 allocs/op
Benchmark100kPods-8   	    1044	   1187247 ns/op	       0 B/op	       0 allocs/op

[ahg-g]

/lgtm
/approve

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 95192bfd4540a7435e8d0b10280c439c54a619d4

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ahg-g, lowang-bh

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• pkg/scheduler/OWNERS [ahg-g]

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