View the number of visible CPU cores

This document describes how to view the number of visible CPU cores for a virtual machine (VM) instance.

When you view the details of a VM , you can verify if the VM has the default number of visible CPU cores, or if this number has been customized. Reducing the number of visible CPU cores for a VM can help reduce licensing costs without reducing Persistent Disk performance limits. However, reducing the number of visible CPU cores might affect network performance.

Before you begin

• If you haven't already, set up authentication . Authentication verifies your identity for access to Google Cloud services and APIs. To run code or samples from a local development environment, you can authenticate to Compute Engine by selecting one of the following options:

  Select the tab for how you plan to use the samples on this page:

  Console

  When you use the Google Cloud console to access Google Cloud services and APIs, you don't need to set up authentication.

  gcloud

  1. Install the Google Cloud CLI. After installation, initialize the Google Cloud CLI by running the following command:

     gcloud  
     init

     If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity .

  2. Set a default region and zone .

  REST

  To use the REST API samples on this page in a local development environment, you use the credentials you provide to the gcloud CLI.

  Install the Google Cloud CLI. After installation, initialize the Google Cloud CLI by running the following command:

  gcloud  
  init

  If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity .

  For more information, see Authenticate for using REST in the Google Cloud authentication documentation.

Required roles

To get the permission that you need to view the details of a VM, ask your administrator to grant you the Compute Instance Admin (v1) ( roles/compute.instanceAdmin.v1 ) IAM role on the VM or project. For more information about granting roles, see Manage access to projects, folders, and organizations .

This predefined role contains the compute.instances.get permission, which is required to view the details of a VM.

You might also be able to get this permission with custom roles or other predefined roles .

View the number of visible CPU cores for a VM

To determine if the number of visible CPU cores was customized for a VM, select one of the following options:

 gcloud compute instances describe VM_NAME 
\
    --zone= ZONE 
 

 advancedMachineFeatures:
  visibleCoreCount: VISIBLE_CORE_COUNT 
... 

 GET https://compute.googleapis.com/compute/v1/projects/ PROJECT_ID 
/zones/ ZONE 
/instances/ VM_NAME 
 

 {
  ...
  "advancedMachineFeatures": {
    visibleCoreCount: VISIBLE_CORE_COUNT 
},
  ...
} 

What's next

• Customize the number of visible cores
• Set the number of threads per core