Symmetric MultiProcessing for the Pintos Instructional Operating System

For the last decade, practical limitations have prevented processor speeds from increasing significantly. To increase throughput, the computing industry has turned to multiprocessing; that is, executing computations in parallel on separate processing units. Making use of these additional units requires support from the operating system (OS). Indeed, most modern operating systems do have the capability of recognizing and utilizing multiprocessor hardware.

Pintos is an instructional operating system used by many institutions to teach important operating systems concepts. Pintos aims to increase student engagement by providing challenging programming projects in which students personally implement many core functionalities of an operating system. However, prior to this work, Pintos was a uniprocessor OS. This makes it difficult for Pintos to expose students to the same synchronization challenges that most modern kernel developers face. In addition, the first structured project, aimed at teaching scheduling policies, requires students to implement an uniprocessor variant of MLFQS scheduler which is no longer used in modern systems.

We implemented Symmetric MultiProcessing (SMP) support in Pintos. We also created a new scheduling assignment to expose students to a multiprocessor proportional-share scheduling policy called Completely Fair Scheduler and to introduce them to the concept of load balancing. Finally, we evaluate the effectiveness of our new Pintos framework in augmenting students’ knowledge of OS scheduling and enhancing their ability to code and debug in a low-level environment.