Abstract
OSCAL, the Operating System Concept Animation Library (http://gaia.ecs.csus.edu/~zhangd/oscal/oscal.htm), contains a set of animated algorithms as Java applets for concepts in operating systems. OSCAL has been used as a teaching and learning tool for the operating system principles course both at CSUS and in universities around the world. Currently, OSCAL consists of animations for: various processor scheduling algorithms (FCFS, RR, SPN, SRT), real-time scheduling algorithms (RMS, ATSD, PTCD),algorithms for critical section problem (Eisenberg-McGuire, semaphore, message-passing, monitor), Solaris RW Lock, classic concurrency control problems (producer-consumer problem, readers-writer problem, barbershop problem), Banker’s algorithm for deadlock avoidance, various page replacement algorithms in virtual memory (random, FIFO, LRU, MFU, Clock), disk scheduling algorithms (FCFS, SSTF, SCAN, C-SCAN, LOOK, C-LOOK), RAID, cache coherency algorithm, and various data link error control (Stop-and-Wait ARQ, Go-Back-n ARQ, Selective-Reject ARQ). This project augments OSCAL with two new animations: (1) the Solaris Time Sharing (TS) scheduling algorithm; and (2) demonstration of the concept for the principle of locality (temporal locality and spatial locality). Solaris TS scheduling is based on the dynamic priority a process is assigned. Each process starts with an initial priority and an associated time quantum to execute. The higher the priority the smaller the time quantum will be. If the process uses up its entire time quantum, then it is re-assigned to a lower priority, as it is deemed CPU intensive, but with a larger time quantum. When a process returns from sleep its priority will be escalated. Temporal locality exhibits that if a particular memory location is referenced, then it is likely that the same location will be referenced again in the near future. On the other hand, spatial locality indicates that if a particular memory location is accessed, the likelihood that its nearby locations will be referenced in the near future is higher. The addition of these two animations will enhance the capabilities of OSCAL, and will help students gain insight, through visualization and interaction, to a working scheduling algorithm in a popular industry-strength operating system (Solaris), and to the fundamental concept of locality of reference. The new animations will prove to be useful tools for both the instructor and students.