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

When youview the details of a VM, youcan verify if the VM has the default number of visible CPU cores, or if thisnumber has been customized. Reducing the number of visible CPU cores for a VMcan help reduce licensing costs without reducing Persistent Disk performance limits.However, reducing the number of visible CPU cores might affect networkperformance.

Before you begin

• If you haven't already, set upauthentication. 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:

     gcloudinit

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

     Note: If you installed the gcloud CLI previously, make sure you have the latest version by runninggcloud components update.
  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:

  gcloudinit

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

  Note: If you installed the gcloud CLI previously, make sure you have the latest version by runninggcloud components update.

  For more information, seeAuthenticate 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 theCompute Instance Admin (v1) (roles/compute.instanceAdmin.v1) IAM role on the VM or project. For more information about granting roles, seeManage 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 withcustom roles or otherpredefined 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, selectone of the following options:

gcloud compute instances describeVM_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