# EnergyUsageSubsystem

> Identifies a device hardware subsystem that can report energy consumption through EnergyUsage.

## Definition

* **Type:** Enum
* **Namespace:** [UnityEngine.AdaptivePerformance](/engine/6000.7/script-reference/unityengine/adaptiveperformance.md)
* **Assembly:** UnityEngine.AdaptivePerformanceModule

```csharp
public enum EnergyUsageSubsystem
```

## Remarks

Pass a value from this enum to [EnergyUsage.Get](/engine/6000.7/script-reference/unityengine/adaptiveperformance/energyusage/get.md) to read how much energy a single subsystem consumed since energy-usage tracking was started or reset with [IEnergyUsageControl.StartEnergyUsageTracking](/engine/6000.7/script-reference/unityengine/adaptiveperformance/ienergyusagecontrol/startenergyusagetracking.md).

Each subsystem reports independently of the others, because devices expose different sets of power monitors. A platform reports only the subsystems its monitors cover and returns an unavailable reading for the rest, so check [EnergyUsageReading.Available](/engine/6000.7/script-reference/unityengine/adaptiveperformance/energyusagereading/available.md) on each reading before you use its values instead of assuming that a subsystem missing on one device is missing on all devices.

The following example tracks energy usage while a component is enabled and logs how much energy the CPU subsystem consumed since tracking started.

## Examples

```csharp
using UnityEngine;
using UnityEngine.AdaptivePerformance;

public class CpuEnergyUsageExample : MonoBehaviour
{
    IAdaptivePerformance adaptivePerformance;
    IEnergyUsageControl energyUsageControl;

    void OnEnable()
    {
        adaptivePerformance = Holder.Instance;
        if (adaptivePerformance == null || !adaptivePerformance.Initialized)
            return;

        energyUsageControl = adaptivePerformance.EnergyUsageControl();
        if (energyUsageControl == null || !energyUsageControl.StartEnergyUsageTracking())
            Debug.Log("Energy-usage tracking isn't available on this device.");
    }

    void Update()
    {
        if (energyUsageControl == null || !energyUsageControl.EnergyUsageTrackingActive)
            return;

        EnergyUsage energyUsage = adaptivePerformance.PerformanceStatus.PerformanceMetrics.EnergyUsage;
        EnergyUsageReading reading = energyUsage.Get(EnergyUsageSubsystem.Cpu);

        // This device doesn't report energy for this subsystem, so skip it.
        if (!reading.Available)
            return;

        Debug.Log($"The CPU used {reading.Energy} microwatt-seconds over {reading.Interval} ms.");
    }

    void OnDisable()
    {
        energyUsageControl?.StopEnergyUsageTracking();
    }
}
```

## Fields

| Value                                                                                                      | Description                                    |
| ---------------------------------------------------------------------------------------------------------- | ---------------------------------------------- |
| [Cpu](/engine/6000.7/script-reference/unityengine/adaptiveperformance/energyusagesubsystem/cpu.md)         | The CPU subsystem.                             |
| [Display](/engine/6000.7/script-reference/unityengine/adaptiveperformance/energyusagesubsystem/display.md) | The display subsystem.                         |
| [Gpu](/engine/6000.7/script-reference/unityengine/adaptiveperformance/energyusagesubsystem/gpu.md)         | The GPU subsystem.                             |
| [Memory](/engine/6000.7/script-reference/unityengine/adaptiveperformance/energyusagesubsystem/memory.md)   | The memory (DRAM) subsystem.                   |
| [Tpu](/engine/6000.7/script-reference/unityengine/adaptiveperformance/energyusagesubsystem/tpu.md)         | The Tensor (neural) processing unit subsystem. |