How to Make Things Faster

Chapter 99. Utilization Targets

I like to tell the (fictional) story of the man who retired and moved to upstate New York. He and his wife—let’s call them Brad and Vonda—had always imagined running a little B&B up on Otsego Lake near Cooperstown, where the Baseball Hall of Fame is. With the nest egg they had saved, they bought a little place and realized their dream. It went better than they had ever imagined. They had ten guest cabins that were routinely booked to capacity. They were having the time of their lives and making more money than they had made from their “real” jobs. They appreciated the irony of that.

One evening, Brad and Vonda were enjoying a warm drink with some of their guests when there came a knock at the door. A man in a suit explained that the famous entertainer, Jennifer something (pick your own favorite), was outside in the car. She had heard so many nice things about the B&V B&B that she wanted to spend the night, along with a three-person entourage. What a fun opportunity! Of course, they’d love for Jennifer to stay the night. Maybe she’d talk about the reunion or sing a song or something. There’s just one catch: the B&V B&B is full tonight. There’s no room!

On a computer, sometimes you may have periods where your workload is completely predictable. In such a case, we say that your request arrival process is deterministic. Some systems have deterministic arrival periods at night, for example, when the online users have all gone home and a batch scheduler ...