This is the solution. Your manager understood his job, and its impact on yours. Everyone should be so lucky. So far, I have been! At my first job, my boss told me right off not to let everyone who comes by add work to my pile. It's hard to do at first. After all, your first reaction is to be helpful. But after a while you see the benefit of being able to to deflect things to your manager and have him prioritize the workload.