Desktop scheduling: how can we know what the user wants?

Current desktop operating systems use CPU utilization (or lack thereof) to prioritize processes for scheduling. This was thought to be beneficial for interactive processes, under the assumption that they spend much of their time waiting for user input. This reasoning fails for modern multimedia applications. For example, playing a movie in parallel with a heavy background job usually leads to poor graphical results, as these jobs are indistinguishable in terms of CPU usage. Suggested solutions involve shifting the burden to the user or programmer, which we claim is unsatisfactory; instead, we seek an automatic solution. Our attempts using new metrics based on CPU usage failed. We therefore propose and implement a novel scheme of identifying interactive and multimedia applications by directly quantifying the I/O between an application and the user (keyboard, mouse, and screen activity). Preliminary results indicate that prioritizing processes according to this metric indeed solves the aforementioned problem, demonstrating that operating systems can indeed provide better support for multimedia and interactive applications. Additionally, once user I/O data is available, it opens intriguing new possibilities to system designers.