Petastorm sharding and setting batch sizes

[Data-drone]

With sharding in petastorm ie:

with peta_conv_train_df.make_torch_dataloader(transform_spec=transform_func,
                                              num_epochs=1,
                                              batch_size=test_batch_size,
                                              cur_shard = curr_shard,
                                              shard_count = num_shards,
                                              reader_pool_type = pool_type) as reader:

Is the batch_size what we want per GPU or for whole cluster. ie in the above if I had:

test_batch_size = 64 then each shard gets 64 or each shard gets 64 / num_shards?