CPU requests and limits in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a CPU request in Kubernetes?

A CPU request is the amount of CPU guaranteed to a container. Kubernetes uses this to decide which node can run the container.

beginner

What happens if a container exceeds its CPU limit in Kubernetes?

If a container uses more CPU than its limit, Kubernetes throttles it to prevent it from using more CPU than allowed.

intermediate

Why should you set both CPU requests and limits?

Setting both ensures your container gets enough CPU to run well (requests) and prevents it from using too much CPU (limits), helping cluster stability.

intermediate

How does Kubernetes use CPU requests during scheduling?

Kubernetes sums CPU requests of all containers on a node and only schedules new containers if the node has enough free CPU to meet the request.

beginner

What unit is used to specify CPU requests and limits in Kubernetes?

CPU is specified in cores or millicores (m). For example, 500m means half a CPU core.

What does a CPU limit do in Kubernetes?

A Prevents a container from using more CPU than the limit by throttling it

B Guarantees the container will always get this CPU amount

C Sets the maximum memory a container can use

D Schedules the container on the node with the most CPU

CPU limits stop containers from using more CPU than allowed by throttling their CPU usage.

What unit is used to specify CPU requests in Kubernetes?

A Bytes

B Cores or millicores (m)

C Milliseconds

D Percentage

CPU is specified in cores or millicores (m), where 1000m equals 1 full CPU core.

If a container has a CPU request of 200m and a limit of 500m, what does this mean?

A It is guaranteed 200m CPU and can use up to 500m CPU

B It can only use 200m CPU and no more

C It must use exactly 500m CPU

D It has no CPU guarantees

The container is guaranteed 200m CPU but can burst up to 500m CPU if available.

What happens if you set a CPU limit but no CPU request?

A The container is guaranteed CPU equal to the limit

B The container can use unlimited CPU

C The container has no guaranteed CPU but cannot exceed the limit

D The container will not start

Kubernetes automatically assigns a request that matches the limit, guaranteeing the container CPU equal to the limit.

Why is it important to set CPU requests in Kubernetes?

A To speed up container startup

B To limit the container's CPU usage

C To increase container memory

D To help Kubernetes schedule containers on nodes with enough CPU

CPU requests tell Kubernetes how much CPU a container needs, helping it schedule containers properly.

Explain the difference between CPU requests and CPU limits in Kubernetes.

Think about what Kubernetes guarantees versus what it restricts.

Describe why setting CPU requests and limits helps maintain cluster stability.

Consider how resources are shared in a busy kitchen.