What is the CPU credit balance in EC2?

Question

I encountered CPU Credit Balance in EC2 monitoring. What is CP loan balance ?

Answer 1

AWS EC2 has 2 different types of instances: Fixed Performance Installations (such as M3, C3, etc.) and Advanced Performance Instances (such as T2). Fixed Performance Instances provides consistent CPU performance, while Burstable Performance Instances provides baseline CPU performance under normal workload. But when the workload increases Burstable Performance Instances , there is the possibility of exploding, i.e. Improve CPU performance.

CPU credit controls the number of processor packets in an instance. You can spend this CPU loan to increase CPU performance during the surge. Suppose you use an instance with 100% processor performance for 5 minutes, you spend 5(ie 5*1.0) CPU Credit. Similarly, if you run an instance with 50% of the processor’s performance within 5 minutes, you will spend 2.5(ie 5*0.5) CPU Credits.

A CPU loan balance is simply the amount of a CPU loan available in your account at any time.

When you create an instance, you will receive an initial processor loan . At each hour, you automatically receive a certain amount of CPU credits (this amount depends on the type of instance). If you have not exploded the performance of the CPU, then the CPU Credit will be added to your credit balance of your account. If you lose processor credit (i.e., the CPU credit balance turns to 0), your instance will work at basic performance.

Read more about CPU Credits here: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/t2-instances.html#t2-instances-cpu-credits

Answer 2

According to the official document:

Amazon EC2 allows you to choose between fixed performance instances (such as M3, C3, and R3) and swell performance instances (such as T2). Utility performance instances provide a base level CPU with the ability to explode above the baseline. Examples of T2 for workloads that do not use the full processor often or sequentially, but sometimes have to burst.

Initial T2 performance and packet ability are controlled by CPU credits. Each T2 instance continuously receives CPU Credits, the speed of which depends on the size of the instance. Instances of T2 CPU Credits are dialed when they are idle, and they use CPU credits when they are active. CPU Credit delivers full processor core performance for one minute .

Answer 3

To expand on the previous answer.

In class instances

t2 uses the expanded CPU model. Instead of constantly accessing the full CPU resources, you get access to the full CPU resources base for the CPU credit model.

When your instance is idling, the instance builds credits up to the cap. Speed ​​and limit depend on the size of the instance.

When you use CPU resources, you spend these loans. Once you are done, your CPU usage is limited to very low until you create more credits.

Answer 4

When your instance uses less CPU resources than its basic performance level allows (for example, when it is idle), unused CPU loans (or the difference between what was earned and what was spent) are stored in the credit balance to increase up to 24 hours, creating CPU loans for a break.