Measuring Operating Systems Performance

This instantly raises a question: what do we mean by performance? Most of us have an informal sense of what we mean. Perhaps we mean we don’t want to wait for our commands to complete. Perhaps we mean we want to run complex calculations on very large data sets fast enough for the results to be useful. Perhaps we mean we want to get the most possible work through a given piece of hardware that we possibly can. Perhaps we mean we want to use as little space as possible on a storage device, or send as few bits across a network as possible. Maybe we care about how long a user has to wait before he starts to see some response from the system, but maybe we care about how long it takes for the entire job to complete.