Operating System notes all units

contains knowledge about- UNIT 1 Introduction: Introduction to OS. Operating system functions, Different types of O.S.: batch process, multi programmed, time sharing, real time, distributed, parallel. System Structure: Computer system operation, I/O structure, storage structure, storage hierarchy, different types of protections, operating system structure (simple, layered, virtual machine), O/S services, system calls. UNIT II CPU scheduling: scheduling criteria, preemptive and non preemptive scheduling, scheduling algorithms, algorithm evaluation, multi processor scheduling. Threads: overview, benefits of threads, user and kernel threads. Process Management: Concept of processes, process states, process control, co oper ating processes, inter process communication. Process Synchronization: background, critical section problem, critical region, synchronization hardware, Classical problems of synchronization, semaphores. UNIT III Deadlocks: Concept of deadlock, deadlock characterization, deadlock prevention, deadlock avoidance, deadlock detection, recovery from deadlock. Memory Management: background, logical vs. physical address space, contiguous memory allocation, paging, segmentation, segmentation with paging. Concept of fragmentation. Virtual Memory: background, demand paging, concept of page replacement, page replacement algorithms , allocation of frames, thrashing. UNIT IV File Systems: file concept, file organization and access methods, allocation methods, directory structure, free space management I/O Management: I/O hardware, polling, interrupts, DMA, kernel I/O subsystem (scheduling, buffering, caching, spooling and device reservation) Disk Management: disk structure, disk scheduling (FCFS, SSTF, SCAN,C SCAN) , disk reliability, disk Performance parameters. Protection and Security: Goals of protection and security, security attacks, authentication, program threats, system threats, threat monitoring.