Asking for feedback?

I am the only intern in a boutique investment bank and I sit next to a director whose team I'm working in.

I sometimes do work for this guy and I have no idea overall how I'm performing in my internship. If it comes to making a decision on if I should be given a full time offer or not, this guys decision will weigh heavily. What's the best way to ask this guy about my performance and how I could improve?