How to check Default data split ratio for RobertaForMaskedLM?

Hey there.
I am performing a pre-training on RoBERTa for masked language modelling and have performed tokenizer from ByteLevelBPETokenizer.

I have got merges.txt and vocab.json and have provided its path to RobertaForMaskedLM in line by line dataset.

My question is - how to know the default split ratio while performing pre-training using Trainer - is there any way to change the data split ratio for train, test and valid ??

Because I am getting the Loss, epochs and and learning rate in the output , but I haven’t provided any particular split ratio explicitly.