Blocking and Nonblocking 1/0 阻塞和非阻塞Wo e Blocking-process suspended until o completed (阻塞一进程挂起直到Wo完成) Easy to use and understand(容易使用和理解 Insufficient for some needs(在某些场合没有效率) Nonblocking -lo call returns as much as available (非阻塞一O调用返回一个代表是否成功的值) User interface, data copy(buffered lO) (用户界面,数据拷贝(对Wo缓冲)) mplemented via multi-threading(通过多线程来实现) Returns quickly with count of bytes read or written (迅速的返回读写的字节数) e Asynchronous-process runs while O executes (异步:在Vo处理的时候进程同时运行) Difficult to use(难以使用) lo subsystem signals process when IO completed 当O操作完成的时候,WO子系统向进程发信号) Applied Operating System Concepts 12.12 Silberschatz, Galvin, and Gagne @199912.12 Silberschatz, Galvin, and Gagne ©1999 Applied Operating System Concepts Blocking and Nonblocking I/O 阻塞和非阻塞I/O • Blocking - process suspended until I/O completed （阻塞—进程挂起直到I/O完成） – Easy to use and understand（容易使用和理解） – Insufficient for some needs（在某些场合没有效率） • Nonblocking - I/O call returns as much as available （非阻塞—I/O调用返回一个代表是否成功的值） – User interface, data copy (buffered I/O) （用户界面，数据拷贝（对I/O缓冲）） – Implemented via multi-threading（通过多线程来实现） – Returns quickly with count of bytes read or written （迅速的返回读写的字节数） • Asynchronous - process runs while I/O executes （异步：在I/O处理的时候进程同时运行） – Difficult to use（难以使用） – I/O subsystem signals process when I/O completed （当I/O操作完成的时候，I/O子系统向进程发信号）