EC2 Burstable high CPUCreditUsage despite CPU under low load

Question

Hello, 
I'm currently having a high CPUCreditUsage on a t3a.micro instance (right below 1) even if the CPU load, monitored from inside the system is very low.

Here's a screenshot of the metrics:
![CPUCreditUsage](/media/postImages/original/IMQUTLg33fTyqjZp5Gu9A82A)

During that period the CPU load, monitored with `htop` was no bigger than 0.2

![htop](/media/postImages/original/IM8cVkcGTLRFSaqXC_-AxtqA)

Am I missing something about the way CPUCredits are measured? Other instances under similar load measure CPUCreditUsage which reflect the inner CPU load.

**Note:** some days ago a process was actually using high CPU resources, so all the instance credits were used, the CPUCreditBalance ended up in zero, and the CPU was throttled. But that issue was fixed, now the actual CPU usage is low (as reported above), and the CPUCreditBalance raised with a low slope during these days up to 50 points (As said, the current CPUCreditUsage is close to, but lower than one, so the Credit balance is raising, just not as fast as I would expect)

Thanks in advance

Accepted Answer

Your running a t3a.micro, therefore the baseline of that instance type is 10% per vCPU. If your over this baseline then you will start to spend the accrued credits. If your constantly over this then you will not accure credits. You will only start to earn credits if your below the baseline.

*If a burstable performance instance needs to burst above the baseline utilization level, it spends the accrued credits. The more credits that a burstable performance instance has accrued, the more time it can burst beyond its baseline when more CPU utilization is needed.*

Each instance size has a different baseline.

Details can be found here.
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/burstable-credits-baseline-concepts.html

Answer

Thanks a lot, I was missing the baseline concept.

EC2 Burstable high CPUCreditUsage despite CPU under low load

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