Learning to Think In Code

This week’s module focused on how operating systems manage I/O devices, hard drives, and the basics of file systems. The main topics we covered were I/O devices, the structure and performance of hard disk drives, files and directories, and finally how a simple file system is implemented. All of these tied back to the bigger idea of how the OS communicates with hardware while keeping everything organized, reliable, and efficient. We discussed I/O devices, where we distinguished between block devices and character devices and the way the OS communicates with both categories. The discussion revealed that disks, keyboards, and USB peripherals, for instance, differed markedly in their performance requirements. I grasped the main ideas but had to struggle a little bit with the concept of hierarchical buses and the reason behind faster devices being nearer to the CPU. It dawned on me that it’s all about minimizing latency and maximizing data transfer rate, thus the concept clicked. Next, we w...

The week was primarily about concurrency, and among the most important things that we studied were condition variables, semaphores, implementation of a bounded buffer, synchronization barriers, the Anderson/Dahlin method, and some typical bugs in concurrency. It is true that all these topics are related, but they all deal with thread coordination in different manners. Condition variables made sense to me once I realized they basically act like a “waiting room” for threads. A thread can go to sleep until some condition becomes true, and another thread signals it when it’s time to move forward. Semaphores felt similar at first, but I learned they’re more like counters that let a certain number of threads access something. The difference between binary and counting semaphores stood out to me. Binary feels like a simple lock, while counting semaphores allow more flexibility depending on the resource. The hardest part this week was keeping the differences between locks and condition variabl...