When you start a VM instance on Compute Engine, the instance uses one of the CPU platforms available on Compute Engine. If you do not actively specify a desired CPU platform, the instance uses the default platform for the zone where the instance will run. You can see a list of zones and their default CPU platforms in the Regions and Zones page. Additionally, each CPU Platform is only available for specific machine types.
On Compute Engine, each virtual CPU (vCPU) is implemented as a single hardware hyper-thread on one of the available CPU Platforms. On Intel Xeon processors, Intel Hyper-Threading Technology allows multiple application threads to run on each physical processor core. You configure your Compute Engine virtual machine instances with one or more of these hyper-threads as vCPUs. The machine type specifies the number of vCPUs that your instance has.
The following CPU platforms are available on Compute Engine:
|CPU Platform||Supported Machine Types||Base Frequency(GHz)||All-Core Turbo Frequency (GHz)||Single-Core Max Turbo Frequency (GHz)||Intel Xeon Scalable Processor (Cascade Lake)|
|Intel Xeon Scalable Processor (Skylake)||2.0||2.7||3.5|
|Intel Xeon E7 (Broadwell E7)||
|Intel Xeon E5 v4 (Broadwell E5)||2.2||2.8||3.7|
|Intel Xeon E5 v3 (Haswell)||2.3||2.8||3.8|
|Intel Xeon E5 v2 (Ivy Bridge)||2.5||3.1||3.5|
|Intel Xeon E5 (Sandy Bridge)||2.6||3.2||3.6|
This page describes the hardware specifications of the CPUs available on Compute Engine but keep in mind that:
- A VM's guest environment will always only see the base clock frequency, regardless of what frequency the VM is actually running at.
- Most VMs get the all-core turbo frequency, even if only the base frequency is advertised to the guest environment.
- C-state is only supported for C2 machines types. For other machine types, C-State or P-State is not supported at this time so idling virtual CPUs within the guest might not work as expected.
- Base clock frequency: A lower bound on CPU frequency, and the frequency at which the TSC (time stamp counter) increments.
- All-cores turbo frequency: The typical frequency at which each CPU runs, if all cores in the socket are non-idle at the same time.