Operating Systems

CPU scheduling determines which process runs next. GATE tests scheduling algorithms, their metrics (waiting time, turnaround time), and preemptive vs non-preemptive behaviour.

Synchronisation ensures correct concurrent access to shared resources. Deadlocks occur when processes wait for each other in a cycle. GATE tests mutual exclusion, semaphores, monitors, and deadlock conditions.

Memory management maps logical addresses to physical memory. Paging eliminates external fragmentation; segmentation reflects program structure. GATE tests address translation, page tables, and fragmentation.

Virtual memory allows processes to use more memory than physically available using demand paging. Page replacement algorithms decide which page to evict on a page fault.

File systems organise persistent storage into files and directories. GATE tests disk scheduling algorithms, file allocation methods, i-node structure, and RAID levels.