From 979ffdf355a4e9404db84b799961db5e65af5473 Mon Sep 17 00:00:00 2001 From: Shannon Kularathna Date: Tue, 27 Apr 2021 21:03:51 +0000 Subject: [PATCH] Clarify use of QoS in eviction ranking --- .../configuration/pod-priority-preemption.md | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/content/en/docs/concepts/configuration/pod-priority-preemption.md b/content/en/docs/concepts/configuration/pod-priority-preemption.md index d6acc80a71..5e75674d73 100644 --- a/content/en/docs/concepts/configuration/pod-priority-preemption.md +++ b/content/en/docs/concepts/configuration/pod-priority-preemption.md @@ -353,13 +353,15 @@ the removal of the lowest priority Pods is not sufficient to allow the scheduler to schedule the preemptor Pod, or if the lowest priority Pods are protected by `PodDisruptionBudget`. -The only component that considers both QoS and Pod priority is -[kubelet out-of-resource eviction](/docs/tasks/administer-cluster/out-of-resource/). -The kubelet ranks Pods for eviction first by whether or not their usage of the -starved resource exceeds requests, then by Priority, and then by the consumption -of the starved compute resource relative to the Pods' scheduling requests. -See -[evicting end-user pods](/docs/tasks/administer-cluster/out-of-resource/#evicting-end-user-pods) +The kubelet uses Priority to determine pod order for [out-of-resource eviction](/docs/tasks/administer-cluster/out-of-resource/). +You can use the QoS class to estimate the order in which pods are most likely +to get evicted. The kubelet ranks pods for eviction based on the following factors: + + 1. Whether the starved resource usage exceeds requests + 1. Pod Priority + 1. Amount of resource usage relative to requests + +See [evicting end-user pods](/docs/tasks/administer-cluster/out-of-resource/#evicting-end-user-pods) for more details. kubelet out-of-resource eviction does not evict Pods when their @@ -367,7 +369,6 @@ usage does not exceed their requests. If a Pod with lower priority is not exceeding its requests, it won't be evicted. Another Pod with higher priority that exceeds its requests may be evicted. - ## {{% heading "whatsnext" %}} * Read about using ResourceQuotas in connection with PriorityClasses: [limit Priority Class consumption by default](/docs/concepts/policy/resource-quotas/#limit-priority-class-consumption-by-default)