better logging and help (#9203)

Author: stas00

examples/seq2seq/finetune_trainer.py

@@ -98,6 +98,7 @@ class DataTrainingArguments:
         metadata={
             "help": "The maximum total sequence length for validation target text after tokenization. Sequences longer "
             "than this will be truncated, sequences shorter will be padded."
+            " This argument is also used to override the ``max_length`` param of ``model.generate``, which is used during ``evaluate`` and ``predict``"
         },
     )
     test_max_target_length: Optional[int] = field(

examples/seq2seq/utils.py

@@ -434,7 +434,8 @@ def use_task_specific_params(model, task):
 
     if task_specific_params is not None:
         pars = task_specific_params.get(task, {})
-        logger.info(f"using task specific params for {task}: {pars}")
+        logger.info(f"setting model.config to task specific params for {task}:\n {pars}")
+        logger.info("note: command line args may override some of these")
         model.config.update(pars)