Metrics analyzed by AWS Compute Optimizer - AWS Compute Optimizer
Enabling memory utilization with the CloudWatch AgentEnabling detailed monitoring in CloudWatch

Metrics analyzed by AWS Compute Optimizer

After you opt in, AWS Compute Optimizer begins analyzing the specifications (vCPUs, memory, storage, and so on) and the utilization metrics of your running resources from a period of the last 14 days. Compute Optimizer requires at least 30 consecutive hours of metrics data from your resource to generate recommendations. After the analysis is completed, which could take up to 12 hours, Compute Optimizer presents its findings on the dashboard page. For more information, see Viewing the AWS Compute Optimizer dashboard.

Compute Optimizer analyzes the following CloudWatch metrics of your EC2 instances by default:

  • CPU utilization - The percentage of allocated EC2 compute units that are in use on the instance. This metric identifies the processing power required to run an application on an instance.

  • Memory utilization - The amount of memory that has been used in some way during the sample period. This metric identifies the memory required to run an application on an instance. Memory utilization is analyzed only for resources that have the unified CloudWatch agent installed on them. For more information, see Enabling memory utilization with the CloudWatch Agent.

  • Network in - The number of bytes received on all network interfaces by the instance. This metric identifies the volume of incoming network traffic to an instance.

  • Network out - The number of bytes sent out on all network interfaces by the instance. This metric identifies the volume of outgoing network traffic from an instance.

  • Local disk input/output (I/O) - The number of input/output operations for the local disk. This metric identifies the performance of the root volume of an instance.

  • Amazon EBS volume read/write throughput and bandwidth - The read/write operations per second, and the read/write bytes per second (displayed as KiB/seconds in the console) of all EBS volumes attached to the instance.

For more information about these metrics, see List the Available CloudWatch Metrics for Your Instances in the Amazon Elastic Compute Cloud User Guide.

Enabling memory utilization with the CloudWatch Agent

Install the CloudWatch agent on your instances to have Compute Optimizer analyze the memory utilization of your instances. Enabling Compute Optimizer to analyze memory utilization data for your instances provides an additional measurement of data that further improves the recommendations provided by the service. For more information about installing the CloudWatch agent, see Collecting Metrics and Logs from Amazon EC2 Instances and On-Premises Servers with the CloudWatch Agent in the Amazon CloudWatch User Guide.

On Linux instances, Compute Optimizer analyses the mem_used_percent metric in the CWAgent namespace, or the legacy MemoryUtilization metric in the System/Linux namespace. On Windows instances, Compute Optimizer analyses the Memory % Committed Bytes In Use metric in the CWAgent namespace. Additionally, the namespace must contain the InstanceId dimension. Compute Optimizer will not be able to collect memory utilization data for your instance if the InstanceId dimension is missing, or if you overwrite it with your own custom dimension name. Namespaces and dimensions are defined in the CloudWatch Agent configuration file. For more information, see Create the CloudWatch Agent Configuration File in the Amazon CloudWatch User Guide.

Enabling detailed monitoring in CloudWatch

Enable detailed monitoring for your resources to allow your instance resources to be monitored at 1-minute increments, rather than the default 5-minute increments. Detailed monitoring provides a higher level of definition for the utilization data that is available to Compute Optimizer. For more information, see Enable or Disable Detailed Monitoring for Your Instances in the Amazon Elastic Compute Cloud User Guide, or Configure Monitoring for Auto Scaling Instances in the Amazon EC2 Auto Scaling User Guide. Additional charges might apply to enable detailed monitoring. For more information, see the Amazon CloudWatch pricing page.