how to run m validation batches after running every n training batches?
🚀 Feature
For example, I'm runing a model on a big dataset. After every 10000 training batches, I'd like to run 1000 validation batches to  check the avg_traning_loss and avg_val_loss.
I tried val_check_interval but it just run all validation dataset, which is too big and time consuming. How to validate only part of the validation data?
This is similar to #2534 with something different.
Thanks a lot!
Ben