Identify and Select a GPU Device

This example shows how to use gpuDevice to identify and select which device you want to use.

To determine how many GPU devices are available in your computer, use the gpuDeviceCount function.

gpuDeviceCount("available")

ans = 2

When there are multiple devices, the first is the default. You can examine its properties with the gpuDeviceTable function to determine if that is the one you want to use.

gpuDeviceTable

ans=2×5 table
    Index        Name         ComputeCapability    DeviceAvailable    DeviceSelected
    _____    _____________    _________________    _______________    ______________

      1      "TITAN RTX"            "7.5"               true              true      
      2      "Quadro K620"          "5.0"               true              false     

If the first device is the device you want to use, you can proceed. To run computations on the GPU, use gpuArray enabled functions. For more information, see Run MATLAB Functions on a GPU.

To use another device, call gpuDevice with the index of the other device.

gpuDevice(2)

ans = 
  CUDADevice with properties:

                      Name: 'Quadro K620'
                     Index: 2
         ComputeCapability: '5.0'
            SupportsDouble: 1
             DriverVersion: 11
            ToolkitVersion: 10.2000
        MaxThreadsPerBlock: 1024
          MaxShmemPerBlock: 49152
        MaxThreadBlockSize: [1024 1024 64]
               MaxGridSize: [2.1475e+09 65535 65535]
                 SIMDWidth: 32
               TotalMemory: 2.1475e+09
           AvailableMemory: 1.6776e+09
       MultiprocessorCount: 3
              ClockRateKHz: 1124000
               ComputeMode: 'Default'
      GPUOverlapsTransfers: 1
    KernelExecutionTimeout: 1
          CanMapHostMemory: 1
           DeviceSupported: 1
           DeviceAvailable: 1
            DeviceSelected: 1