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Chapter 13: I/O SystemsChapter 13: I/O Systems
13.2 Silberschatz, Galvin and GagneOperating System Concepts
Chapter 13: I/O SystemsChapter 13: I/O Systems
I/O Hardware
A...
13.3 Silberschatz, Galvin and GagneOperating System Concepts
ObjectivesObjectives
Explore the structure of an operating sy...
13.4 Silberschatz, Galvin and GagneOperating System Concepts
I/O HardwareI/O Hardware
Incredible variety of I/O devices
Co...
13.5 Silberschatz, Galvin and GagneOperating System Concepts
A Typical PC Bus StructureA Typical PC Bus Structure
13.6 Silberschatz, Galvin and GagneOperating System Concepts
Device I/O Port Locations on PCs (partial)Device I/O Port Loc...
13.7 Silberschatz, Galvin and GagneOperating System Concepts
PollingPolling
Determines state of device
command-ready
busy
...
13.8 Silberschatz, Galvin and GagneOperating System Concepts
InterruptsInterrupts
CPU Interrupt-request line triggered by ...
13.9 Silberschatz, Galvin and GagneOperating System Concepts
Interrupt-Driven I/O CycleInterrupt-Driven I/O Cycle
13.10 Silberschatz, Galvin and GagneOperating System Concepts
Intel Pentium Processor Event-VectorIntel Pentium Processor ...
13.11 Silberschatz, Galvin and GagneOperating System Concepts
Direct Memory AccessDirect Memory Access
Used to avoid progr...
13.12 Silberschatz, Galvin and GagneOperating System Concepts
Six Step Process to Perform DMASix Step Process to Perform D...
13.13 Silberschatz, Galvin and GagneOperating System Concepts
Application I/O InterfaceApplication I/O Interface
I/O syste...
13.14 Silberschatz, Galvin and GagneOperating System Concepts
A Kernel I/O StructureA Kernel I/O Structure
13.15 Silberschatz, Galvin and GagneOperating System Concepts
Characteristics of I/O DevicesCharacteristics of I/O Devices
13.16 Silberschatz, Galvin and GagneOperating System Concepts
Block and Character DevicesBlock and Character Devices
Block...
13.17 Silberschatz, Galvin and GagneOperating System Concepts
Network DevicesNetwork Devices
Varying enough from block and...
13.18 Silberschatz, Galvin and GagneOperating System Concepts
Clocks and TimersClocks and Timers
Provide current time, ela...
13.19 Silberschatz, Galvin and GagneOperating System Concepts
Blocking and Nonblocking I/OBlocking and Nonblocking I/O
Blo...
13.20 Silberschatz, Galvin and GagneOperating System Concepts
Two I/O MethodsTwo I/O Methods
Synchronous Asynchronous
13.21 Silberschatz, Galvin and GagneOperating System Concepts
Kernel I/O SubsystemKernel I/O Subsystem
Scheduling
Some I/O...
13.22 Silberschatz, Galvin and GagneOperating System Concepts
Device-status TableDevice-status Table
13.23 Silberschatz, Galvin and GagneOperating System Concepts
Sun Enterprise 6000 Device-TransferSun Enterprise 6000 Devic...
13.24 Silberschatz, Galvin and GagneOperating System Concepts
Kernel I/O SubsystemKernel I/O Subsystem
Caching - fast memo...
13.25 Silberschatz, Galvin and GagneOperating System Concepts
Error HandlingError Handling
OS can recover from disk read, ...
13.26 Silberschatz, Galvin and GagneOperating System Concepts
I/O ProtectionI/O Protection
User process may accidentally o...
13.27 Silberschatz, Galvin and GagneOperating System Concepts
Use of a System Call to Perform I/OUse of a System Call to P...
13.28 Silberschatz, Galvin and GagneOperating System Concepts
Kernel Data StructuresKernel Data Structures
Kernel keeps st...
13.29 Silberschatz, Galvin and GagneOperating System Concepts
UNIX I/O Kernel StructureUNIX I/O Kernel Structure
13.30 Silberschatz, Galvin and GagneOperating System Concepts
I/O Requests to HardwareI/O Requests to Hardware
OperationsO...
13.31 Silberschatz, Galvin and GagneOperating System Concepts
Life Cycle of An I/O RequestLife Cycle of An I/O Request
13.32 Silberschatz, Galvin and GagneOperating System Concepts
STREAMSSTREAMS
STREAM – a full-duplex communication channel ...
13.33 Silberschatz, Galvin and GagneOperating System Concepts
The STREAMS StructureThe STREAMS Structure
13.34 Silberschatz, Galvin and GagneOperating System Concepts
PerformancePerformance
I/O a major factor in system performa...
13.35 Silberschatz, Galvin and GagneOperating System Concepts
Intercomputer CommunicationsIntercomputer Communications
13.36 Silberschatz, Galvin and GagneOperating System Concepts
Improving PerformanceImproving Performance
Reduce number of ...
13.37 Silberschatz, Galvin and GagneOperating System Concepts
Device-Functionality ProgressionDevice-Functionality Progres...
End of Chapter 13End of Chapter 13
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13.IO systems

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1.Introduction
2.OS Structures
3.Process
4.Threads
5.CPU Scheduling
6.Process Synchronization
7.Dead Locks
8.Memory Management
9.Virtual Memory
10.File system Interface
11.File system implementation
12.Mass Storage System
13.IO Systems
14.Protection
15.Security
16.Distributed System Structure
17.Distributed File System
18.Distributed Co Ordination
19.Real Time System
20.Multimedia Systems
21.Linux
22.Windows

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Transcript of "13.IO systems"

  1. 1. Chapter 13: I/O SystemsChapter 13: I/O Systems
  2. 2. 13.2 Silberschatz, Galvin and GagneOperating System Concepts Chapter 13: I/O SystemsChapter 13: I/O Systems I/O Hardware Application I/O Interface Kernel I/O Subsystem Transforming I/O Requests to Hardware Operations Streams Performance
  3. 3. 13.3 Silberschatz, Galvin and GagneOperating System Concepts ObjectivesObjectives Explore the structure of an operating system’s I/O subsystem Discuss the principles of I/O hardware and its complexity Provide details of the performance aspects of I/O hardware and software
  4. 4. 13.4 Silberschatz, Galvin and GagneOperating System Concepts I/O HardwareI/O Hardware Incredible variety of I/O devices Common concepts Port Bus (daisy chain or shared direct access) Controller (host adapter) I/O instructions control devices Devices have addresses, used by Direct I/O instructions Memory-mapped I/O
  5. 5. 13.5 Silberschatz, Galvin and GagneOperating System Concepts A Typical PC Bus StructureA Typical PC Bus Structure
  6. 6. 13.6 Silberschatz, Galvin and GagneOperating System Concepts Device I/O Port Locations on PCs (partial)Device I/O Port Locations on PCs (partial)
  7. 7. 13.7 Silberschatz, Galvin and GagneOperating System Concepts PollingPolling Determines state of device command-ready busy Error Busy-wait cycle to wait for I/O from device
  8. 8. 13.8 Silberschatz, Galvin and GagneOperating System Concepts InterruptsInterrupts CPU Interrupt-request line triggered by I/O device Interrupt handler receives interrupts Maskable to ignore or delay some interrupts Interrupt vector to dispatch interrupt to correct handler Based on priority Some nonmaskable Interrupt mechanism also used for exceptions
  9. 9. 13.9 Silberschatz, Galvin and GagneOperating System Concepts Interrupt-Driven I/O CycleInterrupt-Driven I/O Cycle
  10. 10. 13.10 Silberschatz, Galvin and GagneOperating System Concepts Intel Pentium Processor Event-VectorIntel Pentium Processor Event-Vector TableTable
  11. 11. 13.11 Silberschatz, Galvin and GagneOperating System Concepts Direct Memory AccessDirect 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
  12. 12. 13.12 Silberschatz, Galvin and GagneOperating System Concepts Six Step Process to Perform DMASix Step Process to Perform DMA TransferTransfer
  13. 13. 13.13 Silberschatz, Galvin and GagneOperating System Concepts Application I/O InterfaceApplication 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
  14. 14. 13.14 Silberschatz, Galvin and GagneOperating System Concepts A Kernel I/O StructureA Kernel I/O Structure
  15. 15. 13.15 Silberschatz, Galvin and GagneOperating System Concepts Characteristics of I/O DevicesCharacteristics of I/O Devices
  16. 16. 13.16 Silberschatz, Galvin and GagneOperating System Concepts Block and Character DevicesBlock and Character Devices Block devices include disk drives Commands include read, write, seek Raw I/O or file-system access Memory-mapped file access possible Character devices include keyboards, mice, serial ports Commands include get, put Libraries layered on top allow line editing
  17. 17. 13.17 Silberschatz, Galvin and GagneOperating System Concepts Network DevicesNetwork Devices Varying enough from block and character to have own interface Unix and Windows NT/9x/2000 include socket interface Separates network protocol from network operation Includes select functionality Approaches vary widely (pipes, FIFOs, streams, queues, mailboxes)
  18. 18. 13.18 Silberschatz, Galvin and GagneOperating System Concepts Clocks and TimersClocks and Timers Provide current time, elapsed time, timer Programmable interval timer used for timings, periodic interrupts ioctl (on UNIX) covers odd aspects of I/O such as clocks and timers
  19. 19. 13.19 Silberschatz, Galvin and GagneOperating System Concepts Blocking and Nonblocking I/OBlocking 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
  20. 20. 13.20 Silberschatz, Galvin and GagneOperating System Concepts Two I/O MethodsTwo I/O Methods Synchronous Asynchronous
  21. 21. 13.21 Silberschatz, Galvin and GagneOperating System Concepts Kernel I/O SubsystemKernel I/O Subsystem Scheduling Some I/O request ordering via per-device queue Some OSs try fairness Buffering - store data in memory while transferring between devices To cope with device speed mismatch To cope with device transfer size mismatch To maintain “copy semantics”
  22. 22. 13.22 Silberschatz, Galvin and GagneOperating System Concepts Device-status TableDevice-status Table
  23. 23. 13.23 Silberschatz, Galvin and GagneOperating System Concepts Sun Enterprise 6000 Device-TransferSun Enterprise 6000 Device-Transfer RatesRates
  24. 24. 13.24 Silberschatz, Galvin and GagneOperating System Concepts Kernel I/O SubsystemKernel I/O Subsystem Caching - fast memory holding copy of data Always just a copy Key to performance Spooling - hold output for a device If device can serve only one request at a time i.e., Printing Device reservation - provides exclusive access to a device System calls for allocation and deallocation Watch out for deadlock
  25. 25. 13.25 Silberschatz, Galvin and GagneOperating System Concepts Error HandlingError 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
  26. 26. 13.26 Silberschatz, Galvin and GagneOperating System Concepts I/O ProtectionI/O Protection User process may accidentally or purposefully attempt to disrupt normal operation via illegal I/O instructions All I/O instructions defined to be privileged I/O must be performed via system calls  Memory-mapped and I/O port memory locations must be protected too
  27. 27. 13.27 Silberschatz, Galvin and GagneOperating System Concepts Use of a System Call to Perform I/OUse of a System Call to Perform I/O
  28. 28. 13.28 Silberschatz, Galvin and GagneOperating System Concepts Kernel Data StructuresKernel Data Structures Kernel keeps state info for I/O components, including open file tables, network connections, character device state Many, many complex data structures to track buffers, memory allocation, “dirty” blocks Some use object-oriented methods and message passing to implement I/O
  29. 29. 13.29 Silberschatz, Galvin and GagneOperating System Concepts UNIX I/O Kernel StructureUNIX I/O Kernel Structure
  30. 30. 13.30 Silberschatz, Galvin and GagneOperating System Concepts I/O Requests to HardwareI/O Requests to Hardware OperationsOperations Consider reading a file from disk for a process: Determine device holding file Translate name to device representation Physically read data from disk into buffer Make data available to requesting process Return control to process
  31. 31. 13.31 Silberschatz, Galvin and GagneOperating System Concepts Life Cycle of An I/O RequestLife Cycle of An I/O Request
  32. 32. 13.32 Silberschatz, Galvin and GagneOperating System Concepts STREAMSSTREAMS STREAM – a full-duplex communication channel between a user- level process and a device in Unix System V and beyond A STREAM consists of: - STREAM head interfaces with the user process - driver end interfaces with the device - zero or more STREAM modules between them. Each module contains a read queue and a write queue Message passing is used to communicate between queues
  33. 33. 13.33 Silberschatz, Galvin and GagneOperating System Concepts The STREAMS StructureThe STREAMS Structure
  34. 34. 13.34 Silberschatz, Galvin and GagneOperating System Concepts PerformancePerformance I/O a major factor in system performance: Demands CPU to execute device driver, kernel I/O code Context switches due to interrupts Data copying Network traffic especially stressful
  35. 35. 13.35 Silberschatz, Galvin and GagneOperating System Concepts Intercomputer CommunicationsIntercomputer Communications
  36. 36. 13.36 Silberschatz, Galvin and GagneOperating System Concepts Improving PerformanceImproving Performance Reduce number of context switches Reduce data copying Reduce interrupts by using large transfers, smart controllers, polling Use DMA Balance CPU, memory, bus, and I/O performance for highest throughput
  37. 37. 13.37 Silberschatz, Galvin and GagneOperating System Concepts Device-Functionality ProgressionDevice-Functionality Progression
  38. 38. End of Chapter 13End of Chapter 13
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