Red Hat build of MicroShift

Prepare a MicroShift workload for low latency

To use low latency, configure pod annotations to set the microshift-low-latency container runtime configuration for your workloads by using the RuntimeClass feature.

Prerequisites

You installed the microshift-low-latency RPM package.
You configured workload partitioning.

Procedure

Use the following example to set the following annotations in the pod spec:

cpu-load-balancing.crio.io: "disable"
irq-load-balancing.crio.io: "disable"
cpu-quota.crio.io: "disable"
cpu-load-balancing.crio.io: "disable"
cpu-freq-governor.crio.io: "<governor>"

Example pod that runs oslat test:

apiVersion: v1
kind: Pod
metadata:
  name: oslat
  annotations:
    cpu-load-balancing.crio.io: "disable"
    irq-load-balancing.crio.io: "disable"
    cpu-quota.crio.io: "disable"
    cpu-c-states.crio.io: "disable"
    cpu-freq-governor.crio.io: "<governor>"
spec:
  runtimeClassName: microshift-low-latency
  containers:
  - name: oslat
    image: quay.io/container-perf-tools/oslat
    imagePullPolicy: Always
    resources:
      requests:
        memory: "400Mi"
        cpu: "2"
      limits:
        memory: "400Mi"
        cpu: "2"
    env:
    - name: tool
      value: "oslat"
    - name: manual
      value: "n"
    - name: PRIO
      value: "1"
    - name: delay
      value: "0"
    - name: RUNTIME_SECONDS
      value: "60"
    - name: TRACE_THRESHOLD
      value: ""
    - name: EXTRA_ARGS
      value: ""
    securityContext:
      privileged: true
      capabilities:
        add:
          - SYS_NICE
          - IPC_LOCK

metadata.annotations.cpu-load-balancing.crio.io

Disables the CPU load balancing for the pod.

metadata.annotations.irq-load-balancing.crio.io

Opts the pod out of interrupt handling (IRQ).

metadata.annotations.cpu-quota.crio.io

Disables the CPU completely fair scheduler (CFS) quota at the pod run time.

metadata.annotations.cpu-c-states.crio.io

Enables or disables C-states for each CPU. Set the value to disable to provide the best performance for a high-priority pod.

metadata.annotations.cpu-freq-governor.crio.io

Sets the cpufreq governor for each CPU. The performance governor is recommended for high-priority workloads.

spec.runtimeClassName

The runtimeClassName must match the name of the performance profile configured in the node. For example, microshift-low-latency.

Disable CPU load balancing only when the CPU manager static policy is enabled and for pods with guaranteed QoS that use whole CPUs. Otherwise, disabling CPU load balancing can affect the performance of other containers in the node.

For the pod to have the Guaranteed QoS class, it must have the same values of CPU and memory in requests and limits. See Guaranteed (Kubernetes upstream documentation)