Customize the number of visible CPU cores

Linux Windows

Customizing the number of visible CPU cores can provide granular control overlicensing costs, while maintaining the performance of networking and persistentdisks. This customization reduces the number of vCPUs that are available to thevirtual machine (VM) instance; it doesn't change the machine type or price.

Compute Engine implements each virtual CPU (vCPU) as a single hardwaremultithread that runs on a physical CPU core. To reduce the number of vCPUs thatare available to a VM, Compute Engine lets you customize the number ofvisible CPU cores.

Visible cores are the CPU cores in the underlying hardware that your VMsconsume. By default, the number of CPU cores that are visible to a VM is thenumber of vCPUs on the machine type divided by the number ofthreads percore:

Visible CPU cores =vCPUs on the machine type /threads per core

For example, thec2-standard-60 machine type specifies 60 vCPUs. Assuming thedefault of 2 threads per core, the number of visible CPU cores is 30. If youreduce the number of visible cores from 30 to 20, the number of functional vCPUsis reduced from 60 to 40.

Consider customizing the number of visible CPU cores if both of the followingapply:

Before customizing the number of vCPUs that are available to a VM, firstconsider using acustom machine type.

Required roles

To get the permissions that you need to customize the number of visible CPU cores, ask your administrator to grant you theCompute Instance Admin (v1) (roles/compute.instanceAdmin.v1) IAM role on the project. For more information about granting roles, seeManage access to projects, folders, and organizations.

This predefined role contains the permissions required to customize the number of visible CPU cores. To see the exact permissions that are required, expand theRequired permissions section:

Required permissions

The following permissions are required to customize the number of visible CPU cores:

  • To customize the number of visible CPU cores during VM creation:
    • compute.instances.create on the project
    • To use a custom image to create the VM:compute.images.useReadOnly on the image
    • To use a snapshot to create the VM:compute.snapshots.useReadOnly on the snapshot
    • To use an instance template to create the VM:compute.instanceTemplates.useReadOnly on the instance template
    • To assign alegacy network to the VM:compute.networks.use on the project
    • To specify a static IP address for the VM:compute.addresses.use on the project
    • To assign an external IP address to the VM when using a legacy network:compute.networks.useExternalIp on the project
    • To specify a subnet for the VM:compute.subnetworks.use on the project or on the chosen subnet
    • To assign an external IP address to the VM when using a VPC network:compute.subnetworks.useExternalIp on the project or on the chosen subnet
    • To set VM instance metadata for the VM:compute.instances.setMetadata on the project
    • To set tags for the VM:compute.instances.setTags on the VM
    • To set labels for the VM:compute.instances.setLabels on the VM
    • To set a service account for the VM to use:compute.instances.setServiceAccount on the VM
    • To create a new disk for the VM:compute.disks.create on the project
    • To attach an existing disk in read-only or read-write mode:compute.disks.use on the disk
    • To attach an existing disk in read-only mode:compute.disks.useReadOnly on the disk
  • To customize the number of visible CPU cores on a group of VMs by using an instance template: You need all the permissions you would use during VM creation and thecompute.instanceTemplates.create on the project

You might also be able to get these permissions withcustom roles or otherpredefined roles.

vCPUs and the number of threads per core

The total vCPUs on a machine type is the number of visible CPU cores multipliedby the number of threads per core. For most machine series, the number ofthreads per core is 2, but you canmanually set the number of threads percore to 1.

The following table shows how visible CPU cores, number of threads per core, andtotal available vCPUs are related using thec2-standard-60 machine type as anexample.

Machine typeVisible CPU coresThreads per coreAvailable vCPUs
c2-standard-6030 (default)2 (default)60
c2-standard-6030 (default)130
c2-standard-60202 (default)40
c2-standard-6020120

Performance considerations

This section explains how reducing the number of visible cores can impact theperformance of your VM.

Persistent disk

The performance limits of persistent disks depend on the machine type andaren't affected by the number of visible CPU cores. For more information, seeBlock storage performance.

Networking egress

The bandwidth limits of networking egress match the machine type and aren'taffected by the number of visible CPU cores. However, networking performancedoes vary depending on the number of vCPUs that are accessible to the VM. Forexample, an2-standard-16 machine type with one visible CPU core might notbe able to fully use a 32 Gbps connection.

Pricing

This section explains how reducing the number of visible cores can impact thecost of your VMs.

Operating system licensing costs

You can lower licensing costs for some operating systems by reducing thenumber of visible CPU cores. Applicable operating systems are those thatcharge you for each vCPU that is available to the VM; for example, WindowsServer and SQL Server. For more information about the licensing options forthese operating systems on Compute Engine, seeMicrosoftlicenses.

VM costs, quota, and capacity

VM costs, quota, and capacity remain the same when you customize the number ofvisible CPU cores because Compute Engine charges, tracks quota, andallocates space on machine types for VMs as if they are using the number ofCPU cores of the machine type. For more information about howCompute Engine bills for VMs, seeVM instance pricing.

Limitations

  • You cannot customize the number of visible CPU cores while a VM is in theRUNNING state. For more information about VM states, seeVM instancelifecycle.

  • In the Google Cloud console, when the number of visible cores is reduced,the CPU utilization metric can't scale up to 100%. It is limited to thenumber of visible CPU cores divided by the maximum number of CPU cores.

  • You can't use this feature to customize the number of visible CPU cores forbare metal instances.

Supported machine types and valid values for each

Manymachine types support customization ofthe number of visible CPU cores. The value for the visible CPU core count mustbe a whole number. The maximum value is the number of vCPUs—or GPUs foraccelerator-optimized machine types—on the machine type divided by thenumber ofthreads per core forthe VM.

The following table shows the machine types that support this customization,along with the corresponding valid values for visible CPU cores for machinetypes in those families.

Machine type familyPredefined vCPU count*Valid values for visible CPU cores
General-purpose
C4D≤ 192Any
C4D> 192Multiples of 2
C44, 8, 16, 24, 32, 48Any
C496Multiples of 2
C4144Multiples of 3
C4192Multiples of 4
C4288Multiples of 6
C3D≤ 180Any
C3D360Multiples of 2
C34, 8, 22, 44Multiples of 1
C388Multiples of 2
C3176Multiples of 4
E2≤ 32Any
N2≤ 32Any
N2> 32Multiples of 2
N2D≤ 24Any
N2D> 24Multiples of 2
N4≤ 80Any
N4D≤ 96Any
N1≤ 64Any
N1> 64Multiples of 2
N1 (TPU optimized)48Any
N1 (TPU optimized)96Multiples of 2
Storage-optimized
Z3≤ 44Any
Z388Multiples of 2
Z3176Multiples of 4
Compute-optimized
H4D192Multiples of 4
H388Multiples of 4
C24, 8, 16, 30Any
C260Multiples of 2
Memory-optimized
M416, 28, 32, 56Any
M464, 112Multiples of 2
M4224Multiples of 4
M3128Multiples of 2
M332, 64Any
M2208Multiples of 4
M2416Multiples of 8
M140Any
M180, 96Multiples of 2
M1160Multiples of 4
Accelerator-optimized
A4224Multiples of 2
A326, 52, 104, 208, 224Multiples of 2
A2≤ 48Any
A296Multiples of 2
G2≤ 48Any
G296Multiples of 2
G4All machine typesMultiples of 2
* The name for most machine typescontain the vCPU count. However, for accelerator-optimized machine types otherthan G2 and G4, the name for the machine type contains the predefined GPU count.To see the vCPU count for the accelerator-optimized machine types, review theAccelerator-optimized machine familydocumentation.

Customize the number of visible CPU cores during VM creation

To customize the number of visible CPU cores while creating a single VM, followthe steps explained in this section.

The following example shows how to create a SQL Server VM with a reduced numberof visible CPU cores.

Console

To customize the number of visible CPU cores while creating a VM, do thefollowing:

  • InMachine configuration>Advanced configurations>Visible core count, select the number of visible cores.

gcloud

To create a SQL Server VM with a reduced number of visible CPU cores, usethe followinggcloud compute instances createcommand:

gcloud compute instances createVM_NAME \    --image-project=windows-sql-cloud \    --image-family=sql-ent-2019-win-2019 \    --machine-type=MACHINE_TYPE \    --visible-core-count=VISIBLE_CORE_COUNT \    --zone=ZONE

Replace the following:

  • VM_NAME: the name of the VM.

  • MACHINE_TYPE: a supported machine type, forexample,c2-standard-60.

  • VISIBLE_CORE_COUNT: the number of visible CPUcores. For example, when using thec2-standard-60 machine type, if setto20, and the number of threads per core is2, 40 of the 60 CPUs arevisible.

  • ZONE: the zone to create the VM in.

REST

To create a SQL Server VM with a reduced number of visible CPU cores, usethe followinginstances.insertmethod:

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances{  "name": "VM_NAME",  ...  "advanced_machine_features": {    ...    "visibleCoreCount": "VISIBLE_CORE_COUNT"  },  ...}

Replace the following:

  • PROJECT_ID: the ID of the project.

  • ZONE: the zone in which to create the VM.

  • VM_NAME: the name of the VM.

  • VISIBLE_CORE_COUNT: the number of visible CPUcores. For example, when using thec2-standard-60 machine type, if setto20, and the number of threads per core is2, 40 of the 60 CPUs arevisible.

Customize the number of visible CPU cores on a group of VMs by using an instance template

To customize the number of visible CPU cores while creating a VM by using aninstance template, follow the steps explained in this section.

The following example shows how to create a group of identical SQL Server VMswith a reduced number of visible CPU cores by using an instance template.

Console

To customize the number of visible CPU cores while creating an instancetemplate, do the following:

  • InMachine configuration>Advanced configurations>Visible core count, select the number of visible cores.

gcloud

  1. Create an instance template for SQL Server VMs, each with a reducednumber of visible CPU cores, by using the followinggcloud computeinstance-templates createcommand:

    gcloud compute instance-templates createINSTANCE_TEMPLATE_NAME \   --image-project=windows-sql-cloud \   --image-family=sql-ent-2019-win-2019 \   --machine-type=MACHINE_TYPE \   --visible-core-count=VISIBLE_CORE_COUNT \   --zone=ZONE

    Replace the following:

    • INSTANCE_TEMPLATE_NAME: the name of theinstance template.

    • MACHINE_TYPE: a supported machine type, forexample,c2-standard-60.

    • VISIBLE_CORE_COUNT: the number of visibleCPU cores. For example, when using thec2-standard-60 machine type,if set to20, and the number of threads per core is2, 40 of the60 CPUs are visible.

    • ZONE: the zone to create the VMs in.

  2. Create the SQL Server VMs, each with a reduced number of visible CPUcores, by using the followinggcloud compute instances createcommand:

    gcloud compute instances createINSTANCE_NAMES \   --source-instance-template=INSTANCE_TEMPLATE_NAME

    Replace the following:

    • INSTANCE_NAMES: the names of the VMs,separated by spaces, to create from the instance template

    • INSTANCE_TEMPLATE_NAME: the name of theinstance template from which to create the VMs

REST

  1. Create an instance template for SQL Server VMs, each with a reduced numberof visible CPU cores, by using the followinginstanceTemplates.insertmethod:

    POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/instanceTemplates{ "name": "INSTANCE_TEMPLATE_NAME", ... "advanced_machine_features": {   ...   "visible_core_count": "VISIBLE_CORE_COUNT" }, ...}

    Replace the following:

    • PROJECT_ID: the ID of the project.

    • INSTANCE_TEMPLATE_NAME: the name of theinstance template.

    • VISIBLE_CORE_COUNT: the number of visibleCPU cores. For example, when using thec2-standard-60 machine type,if set to20, and the number of threads per core is2, 40 of the60 CPUs are visible.

  2. Create the SQL Server VMs, each with a reduced number of visible CPUcores, by using the followinginstances.insertmethod:

    POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances?sourceInstanceTemplate=INSTANCE_TEMPLATE_NAME{ "name": "VM_NAME", ...}

    Replace the following:

    • PROJECT_ID: the ID of the project

    • ZONE: the zone to create the VM in

    • INSTANCE_TEMPLATE_NAME: the name of theinstance template from which to create the VMs

    • VM_NAME: the name of the VM to create fromthe instance template

Customize the number of visible CPU cores

To customize the number of visible CPU cores on an existing VM, follow thesteps explained in this section.

If you customized the number of visible CPU cores on a group of VMs by using aninstance template, you must create a new instance template and then create newVMs from that instance template. For more information about instance templates,seeInstance templates.

Console

To customize the number of visible CPU cores on an existing VM, do thefollowing:

  1. Stop the VM.

  2. InMachine configuration>Advanced configurations>Visible core count, select the number of visiblecores.

  3. Restart the VM.

gcloud

To update the value for the number of visible CPU cores on an existing VM,use the following steps. For more information, seeUpdate instanceproperties.

  1. Export the existing VM properties to a file by using thegcloudcompute instances exportcommand.

  2. In the file containing the exported properties, modify or add the valuefor the following:

    advancedMachineFeatures: visibleCoreCount:VISIBLE_CORE_COUNT

  3. Update the VM's properties by using thegcloud compute instancesupdate-from-filecommand with--most-disruptive-allowed-action=RESTART.

REST

To update the visible CPU core count of the VM, use the followinginstances.update method:

PUT https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances/VM_NAME?most_disruptive_allowed_action=RESTART{  ...  "advanced_machine_features": {    ...    "visible_core_count": "VISIBLE_CORE_COUNT"  },  ...}

Replace the following:

  • PROJECT_ID: the ID of the project

  • ZONE: the zone that contains the VM

  • VM_NAME: the name of the VM from which toexport properties

  • VISIBLE_CORE_COUNT: the number of visible CPUcores

What's next

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Last updated 2025-12-15 UTC.