Pod Priority Classes

Overview

Hydrolix uses Kubernetes priority for pod scheduling and eviction. If a pod cannot be scheduled, the scheduler tries to preempt (evict) lower priority pods to make scheduling of the pending pod possible.

Terminology

Term	Description
Priority Class	PriorityClass is a non-namespaced object that defines a mapping from a priority class name to the integer value of the priority.
Priority	Priority indicates the importance of a pod relative to other pods.
Preemption Policy	Preemption policy decides if a lower priority pod is evicted to accommodate the higher priority pods. Allowed values are Never and PreemptLowerPriority.

Priority classes

Hydrolix uses these priority classes:

Name (priorityClassName)	Value (value)	Preemption Policy (preemptionPolicy)	Built-in or custom
system-node-critical	2_000_001_000	PreemptLowerPriority	Kubernetes built-in priority class
system-cluster-critical	2_000_000_000	PreemptLowerPriority	Kubernetes built-in priority class
hdx-critical	10_000	PreemptLowerPriority	Custom Hydrolix priority class
vector	10_000	PreemptLowerPriority	Custom Hydrolix priority class
hdx-highest	9_900	PreemptLowerPriority	Custom Hydrolix priority class
hdx-high	9_800	PreemptLowerPriority	Custom Hydrolix priority class
hdx-medium	9_700	PreemptLowerPriority	Custom Hydrolix priority class
hdx-low	9_600	PreemptLowerPriority	Custom Hydrolix priority class
hdx-lowest	9_500	PreemptLowerPriority	Custom Hydrolix priority class