Why using "ratio" argument? about mt-dnn

[namisan]

@svboeing ratio only cares about the first tasks and treats other tasks as additional tasks for performance boost. Please refer our NAACL paper for details.

[namisan]

We implemented several variants of MTL training. The ratio is from our NAACL19 paper, attached https://arxiv.org/pdf/1809.06963.pdf. You can try it on a specific task, which may give some improvement.

[v1nc3nt27]

So, the purpose of the ratio parameter is, given one enormous dataset and some smaller ones, you can reduce the bigger one's impact, thus preventing it to dominate the learning process?
Also, I was wondering; if you do not use the ratio parameter, you will actually train on ALL datasets, is that correct? It's not that some of the smaller ones might get dropped and you end up only training on the big ones?