Change:
var possibleLimitingReason, possibleLimitingMessage string if args.DesiredReplicas > args.CurrentReplicas { <del> scaleUpLimit := calculateScaleUpLimitWithScalingRules(args.CurrentReplicas, a.scaleUpEvents[args.Key], args.ScaleUpBehavior) </del> <ins> scaleUpLimit := calculateScaleUpLimitWithScalingRules(args.CurrentReplicas, a.scaleUpEvents[args.Key], a.scaleDownEvents[args.Key], args.ScaleUpBehavior) </ins> if scaleUpLimit < args.CurrentReplicas { // We shouldn't scale up further until the scaleUpEvents will be cleaned up scaleUpLimit = args.CurrentReplicas

Discussion:
We created an hpa as following: Then started a deployment with 4 replicas and made the CPU utilization about 10%, which proposed to double the replicas, and it did work: Then we changed the CPU utilization to about 1%, which would trigger scaling down and would kill 2 pods only for scaleDown behavior: Then changed the CPU utilization to about 20%, which would trigger scaling up: It did scale up, and for our expectation, it should be scaled to 620/5=24 but would be limited by scaleUp behavior as 4(1+300%)=16, but in fact, it was just scaled up to 8 It would be scaled up to 16 in last scaling actions Start an hpa with a scaleUp behavior which has little long period and a little great Percent value, then start a deployment with a container whose CPU utilization could be controlled easily. Change the CPU utilization to make it scale up within limit, scale down a little, and scale up again without limit. I think it is caused by , this function seems that it just considered about scaleUp event history when calculate scaleUp limit (so does calculate scaleDown limit). I think it is a bit unreasonable. Does this action match the design? Or it does be a bug? <details</details<details</details<details</details<details</details<details</details<details</details
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/sig autoscaling
From what I understand, we observed the following behaviour: , there are pods. The HPA scales up new pods, so we have in total. , pods are scaled down, so we have in total. HPA calculates the desired Replicas with . Since all scaling events happened within the policies , the policy value of kicks in and should allow scaling up to . But it only scaled to .

I think that there is a bug in the following code: See the comments in the following snippets for an explanation: With a of 2, the is as follows: I will think of a possible solution to the problem and would like to contribute once I've made some progress on that :)
In fact, I knew this was caused by the calculating method of "getReplicasChangePerPeriod" and mentioned it in the "Anything else we need to know" of this issue. What I wonder now is that if it is an expected action or it is just a bug. If it quite is a bug, I hope I could contribute as well.
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