如何确保tensorflow在会话中使用所有cpu核心？

import tensorflow as tf

sess = tf.Session()

devices = sess.list_devices()

cpu_devices = [device.name for device in devices if device.device_type == 'CPU']

config = tf.ConfigProto(device_count={'CPU': len(cpu_devices)}, allow_soft_placement=True)
config.gpu_options.allow_growth = True
config.gpu_options.per_process_gpu_memory_fraction = 0.1
config.log_device_placement = True
config.allow_soft_placement = True
config.intra_op_parallelism_threads = len(cpu_devices)
config.inter_op_parallelism_threads = len(cpu_devices)

with tf.Session(config=config) as sess:
    # 在此处执行TensorFlow计算图