Computer Operating System - Lecture 13: I/O System - Nguyen Thanh Son

Nội dung text: Computer Operating System - Lecture 13: I/O System - Nguyen Thanh Son

1. Chapter’s Content  I/O Hardware  Application I/O Interface  Kernel I/O Subsystem  Transforming I/O Requests to Hardware Operations  Streams  Performance BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 2
2. Typical PC Bus Structure BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 4
3. Polling  Determines state of device  command-ready  busy  Error  Busy-wait cycle to wait for I/O from device BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 6
4. Interrupt-Driven I/O Cycle BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 8
5. Direct Memory Access  Used to avoid programmed I/O for large data movement  Requires DMA controller  Bypasses CPU to transfer data directly between I/O device and memory BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 10
6. Application I/O Interface  I/O system calls encapsulate device behaviors in generic classes  Device-driver layer hides differences among I/O controllers from kernel  Devices vary in many dimensions  Character-stream or block  Sequential or random-access  Sharable or dedicated  Speed of operation  read-write, read only, or write only BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 12
7. Characteristics of I/O Devices BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 14
8. Network Devices  Varying enough from block and character to have own interface  Unix and Windows NT/9i/2000 include socket interface  Separates network protocol from network operation  Includes select functionality  Approaches vary widely (pipes, FIFOs, streams, queues, mailboxes) BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 16
9. Blocking and Nonblocking I/O  Blocking - process suspended until I/O completed  Easy to use and understand  Insufficient for some needs  Nonblocking - I/O call returns as much as available  User interface, data copy (buffered I/O)  Implemented via multi-threading  Returns quickly with count of bytes read or written  Asynchronous - process runs while I/O executes  Difficult to use  I/O subsystem signals process when I/O completed BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 18
10. Sun Enterprise 6000 Device-Transfer Rates BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 20
11. Error Handling  OS can recover from disk read, device unavailable, transient write failures  Most return an error number or code when I/O request fails  System error logs hold problem reports BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 22
12. UNIX I/O Kernel Structure BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 24
13. Life Cycle of An I/O Request BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 26
14. The STREAMS Structure BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 28
15. Intercomputer Communications BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 30
16. Device-Functionality Progression BK TP.HCM 07-Feb-17 Faculty of Computer Science & Engineering 32