Source code for libertem.common.backend

import os
from typing import Optional

Get and set environment variables that indicate to use CPU or GPU processing and
the appropriate device IDs

This allows configuring a Dask worker or inline executor to use CPU or a
particular GPU, which allows simultaneous use of all GPUs and CPUs on a
processing node without oversubscription.

Internally, this gets and sets the environment variables

See :ref:`udf cuda` for details on how to run UDFs with CUDA support and
:ref:`debugging udfs` for information on how to use these functions to control
where an :class:`~libertem.executor.inline.InlineJobExecutor` runs tasks.

[docs]def get_use_cuda() -> Optional[int]: ''' .. versionadded:: 0.6.0 Returns ------- id : int or None CUDA device ID to use. ''' ret = os.environ.get("LIBERTEM_USE_CUDA") if ret is not None: return int(ret) else: return None
[docs]def set_use_cuda(cuda_device: int): ''' This sets a CUDA device ID and unsets any CPU ID .. versionadded:: 0.6.0 Parameters ---------- cuda_device : int CUDA device ID to use ''' os.environ["LIBERTEM_USE_CUDA"] = str(cuda_device) os.environ.pop("LIBERTEM_USE_CPU", None)
[docs]def get_use_cpu(): ''' .. versionadded:: 0.6.0 Returns ------- id : int or None CPU device ID to use. Currently there is no pinning, i.e. the value itself is ignored. :code:`None` means "don't use CPU" and any integer means "use CPU". Default is 0 if no settings were applied before. ''' ret = os.environ.get("LIBERTEM_USE_CPU") if ret is not None: ret = int(ret) elif get_use_cuda() is None: # If no variable is set, return CPU 0 # For example inline executor or test code ret = 0 return ret
[docs]def set_use_cpu(cpu: int): ''' This sets a CPU device ID and unsets any CUDA ID .. versionadded:: 0.6.0 Parameters ---------- cpu : int CPU to use. The value is currently ignored, i.e. any CPU is used without pinning ''' os.environ.pop("LIBERTEM_USE_CUDA", None) os.environ["LIBERTEM_USE_CPU"] = str(cpu)
[docs]def get_device_class(): ''' .. versionadded:: 0.6.0 Returns ------- class : str Device class to use. Can be 'cpu' or 'cuda'. Default is 'cpu' if no settings were applied before. ''' cuda = get_use_cuda() cpu = get_use_cpu() if cpu is not None and cuda is not None: raise RuntimeError( "Both LIBERTEM_USE_CPU and LIBERTEM_USE_CUDA set, expecting at most one" ) if cuda is not None: return "cuda" else: return "cpu"