• Khoa học máy tính - Chapter 13: File systemsKhoa học máy tính - Chapter 13: File systems

    Files are structured or unstructured (byte stream) File system provides: File organizations (sequential, direct, indexed) Directories for grouping of related files logically Sharing and protection of files Disk space allocation, typically indexed File map table (FMT) stores allocation information File control block (FCB) stores information a...

    ppt65 trang | Chia sẻ: nguyenlam99 | Ngày: 10/01/2019 | Lượt xem: 17 | Lượt tải: 0

  • Khoa học máy tính - Chapter 12: Virtual memoryKhoa học máy tính - Chapter 12: Virtual memory

    Which page should VM manager remove from memory to make space for a new page? Page replacement algorithms exploit locality of reference LRU has stack property, but is expensive NRU algorithms are used in practice E.g., clock algorithms How much memory should manager allocate? Use working set model to avoid thrashing Copy-on-write can be used...

    ppt57 trang | Chia sẻ: nguyenlam99 | Ngày: 10/01/2019 | Lượt xem: 16 | Lượt tải: 0

  • Khoa học máy tính - Chapter 11: Memory managementKhoa học máy tính - Chapter 11: Memory management

    Allocation/deallocation of memory can lead to fragmentation: internal or external First-fit, next-fit and best-fit strategies try to reduce fragmentation buddy systems and power-of-2 allocators eliminate external fragmentation Noncontiguous allocation reduces external fragmentation Requires use of the memory management unit (MMU) of CPU Kernel...

    ppt50 trang | Chia sẻ: nguyenlam99 | Ngày: 10/01/2019 | Lượt xem: 15 | Lượt tải: 0

  • Khoa học máy tính - Chapter 10: Synchronization and scheduling in multiprocessor operating systemsKhoa học máy tính - Chapter 10: Synchronization and scheduling in multiprocessor operating systems

    Multiprocessor OS algorithms must be scalable Use of special kinds of locks: Spin locks and sleep locks Important scheduling concepts in multiprocessor OSs: Affinity scheduling Coscheduling Process shuffling

    ppt30 trang | Chia sẻ: nguyenlam99 | Ngày: 10/01/2019 | Lượt xem: 16 | Lượt tải: 0

  • Khoa học máy tính - Chapter 9: Message passingKhoa học máy tính - Chapter 9: Message passing

    Message passing paradigm realizes exchange of information among processes without using shared memory Useful in: microkernel-based OSs, client–server computing, higher-level communication protocols, and parallel or distributed programs Sender/receiver naming: symmetric, asymmetric, indirect (mailbox) Message passing is employed in higher-level p...

    ppt26 trang | Chia sẻ: nguyenlam99 | Ngày: 10/01/2019 | Lượt xem: 14 | Lượt tải: 0

  • Khoa học máy tính - Chapter 8: DeadlocksKhoa học máy tính - Chapter 8: Deadlocks

    Deadlock: set of processes wait indefinitely for events because each of the events can be caused only by other processes in the set Resource deadlock arises when: Resources are nonshareable and nonpreemptible Hold-and-wait Circular wait exists OS can discover a deadlock by analyzing the allocation state of a system Use RRAG, WFG or matrix mod...

    ppt41 trang | Chia sẻ: nguyenlam99 | Ngày: 10/01/2019 | Lượt xem: 16 | Lượt tải: 0

  • Khoa học máy tính - Chapter 7: SchedulingKhoa học máy tính - Chapter 7: Scheduling

    Different scheduling policies Time-sharing: Multilevel adaptive scheduling Fair share scheduling Real-time: Deadline scheduling Rate monotonic scheduling Performance analysis is used to study and tune performance of scheduling policies

    ppt54 trang | Chia sẻ: nguyenlam99 | Ngày: 10/01/2019 | Lượt xem: 16 | Lượt tải: 0

  • Khoa học máy tính - Chapter 6: Process synchronizationKhoa học máy tính - Chapter 6: Process synchronization

    Process synchronization is a generic term for data access synchronization and control synchronization A race condition occurs when actions of concurrent processes may have unexpected consequences Avoided through mutual exclusion Avoidance of race conditions is a primary issue in process synchronization Critical section: section of code that acc...

    ppt64 trang | Chia sẻ: nguyenlam99 | Ngày: 10/01/2019 | Lượt xem: 16 | Lượt tải: 0

  • Khoa học máy tính - Chapter 5: Processes and threadsKhoa học máy tính - Chapter 5: Processes and threads

    A thread is an alternative model of execution of a program Overhead of switching between threads is much less than the overhead of switching between processes Three models of threads: Kernel-level threads User-level threads Hybrid threads Thread models have different implications for switching overhead, concurrency, and parallelism

    ppt48 trang | Chia sẻ: nguyenlam99 | Ngày: 10/01/2019 | Lượt xem: 14 | Lượt tải: 0

  • Khoa học máy tính - Chapter 4: Structure of operating systemsKhoa học máy tính - Chapter 4: Structure of operating systems

    Layered design used the principle of abstraction to control complexity of designing the OS The virtual machine operating system (VM OS) supported operation of several OSs on a computer simultaneously Create a virtual machine for each user In a kernel-based design, kernel is the core of the OS, which invokes the nonkernel routines to implement op...

    ppt35 trang | Chia sẻ: nguyenlam99 | Ngày: 10/01/2019 | Lượt xem: 16 | Lượt tải: 0