tf.config.set_logical_device_configuration

Set the logical device configuration for a tf.config.PhysicalDevice.

Used in the notebooks

Used in the guide

A visible tf.config.PhysicalDevice will by default have a single tf.config.LogicalDevice associated with it once the runtime is initialized. Specifying a list of tf.config.LogicalDeviceConfiguration objects allows multiple devices to be created on the same tf.config.PhysicalDevice.

The following example splits the CPU into 2 logical devices:

physical_devices = tf.config.list_physical_devices('CPU')
assert len(physical_devices) == 1, "No CPUs found"
# Specify 2 virtual CPUs. Note currently memory limit is not supported.
try:
  tf.config.set_logical_device_configuration(
    physical_devices[0],
    [tf.config.LogicalDeviceConfiguration(),
     tf.config.LogicalDeviceConfiguration()])
  logical_devices = tf.config.list_logical_devices('CPU')
  assert len(logical_devices) == 2

  tf.config.set_logical_device_configuration(
    physical_devices[0],
    [tf.config.LogicalDeviceConfiguration(),
     tf.config.LogicalDeviceConfiguration(),
     tf.config.LogicalDeviceConfiguration(),
     tf.config.LogicalDeviceConfiguration()])
except:
  # Cannot modify logical devices once initialized.
  pass

The following example splits the GPU into 2 logical devices with 100 MB each:

physical_devices = tf.config.list_physical_devices('GPU')
try:
  tf.config.set_logical_device_configuration(
    physical_devices[0],
    [tf.config.LogicalDeviceConfiguration(memory_limit=100),
     tf.config.LogicalDeviceConfiguration(memory_limit=100)])

  logical_devices = tf.config.list_logical_devices('GPU')
  assert len(logical_devices) == len(physical_devices) + 1

  tf.config.set_logical_device_configuration(
    physical_devices[0],
    [tf.config.LogicalDeviceConfiguration(memory_limit=10),
     tf.config.LogicalDeviceConfiguration(memory_limit=10)])
except:
  # Invalid device or cannot modify logical devices once initialized.
  pass

device The PhysicalDevice to configure.
logical_devices (optional) List of tf.config.LogicalDeviceConfiguration objects to allocate for the specified PhysicalDevice. If None, the default configuration will be used.

ValueError If argument validation fails.
RuntimeError Runtime is already initialized.