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Reference
- A. Silberschatz, G. Gagne, and P. B. Galvin,
Operating System Concepts Mehdi Kargahi ECE Department University - - PowerPoint PPT Presentation
Operating System Concepts Mehdi Kargahi ECE Department University - - PowerPoint PPT Presentation
Operating System Concepts Mehdi Kargahi ECE Department University of Tehran Spring 2008 1 2/4/2008 Reference A. Silberschatz, G. Gagne, and P. B. Galvin, Operating System Concepts, 7th Ed., 2005. 2/4/2008 2 Course Plan
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Course Plan
1.
Theoretical concepts
- Exercises
- Quiz
- Midterm
- Final
2.
Class participation
3.
Projects
- Linux & Windows
- Small scale kernel programming
4.
Exercise class participation
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Course Outline
Introduction (Terminologies & Overview) Different Structures of Operating Systems Processes and Threads CPU Scheduling (Approaches and Algorithms) Process Synchronization: Facts and Mechanisms Resource Sharing and Deadlock Main and Virtual Memory Management Storage Management Protection & Special Purpose Systems
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Components of a Computer System
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Definitions
User View
Single-user (ease of use, performance) User at a terminal of a mainframe (fair sharing) User at a workstation on a network of servers (a tradeoff
between usability & resource util.)
PDAs (performance/amount of battery life) Embedded systems (almost no user intervention)
System View
Efficient and fair allocation of resources Controlling programs to prevent errors and improper use of the
computer (operations and I/O devices)
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Computer-System Organization
Firmware: Bootstrap program (in ROM or
EEPROM)
Initializes CPU registers, device controllers, memory
contents
Locates and loads into memory the OS kernel
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How the OS Discovers the Occurrence
- f an Event
Polling Interrupt
From hardware by a signal sent to the CPU From software by system call (monitor call)
Interrupt time line for a single process doing output
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Interrupts
Interrupts inform the completion of I/O to the CPU Interrupt Service Routine (ISR) Device drivers? Typically: A device driver for each device controller! Examples Direct Memory Access (DMA) What OS does with respect to DMA?
Determination of buffers, pointers, and counters for the I/O
device
Sending the start command The Completion of transfer will be notified by an interrupt
DMA steals memory cycles from CPU to access the bus
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The Interplay of Components of a Computer System
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Computer-System Architecture
Single-Processor Systems Multiprocessor Systems Clustered Systems
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Single-Processor Systems
Range from PDAs to mainframes They may have special-purpose processors for I/O
devices
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Multi-Processor (Tightly-Coupled) Systems
Sharing
the computer bus, sometimes the clock, memory, and
peripheral devices Main advantages
Increased throughput: the speedup with N processors in not
N due to overheads, contention for shared resources, and that the degree of requests is not N times of a single-processor system
Economy of scale: due to sharing of resources Increased reliability: just slows down due to failure
Graceful degradation Fault tolerance: differs from graceful degradation
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Multi-Processor (Tightly-Coupled) Systems
Two types (HW/SW)
Asymmetric multiprocessing
Master-slave relationship (e.g., SunOS Ver. 4)
Symmetric multiprocessing (SMP)
E.g., Windows, Linux, and Mac OS Multi-core CPUs
Blade servers
Multiple processor boards, I/O boards, and
networking boards on the same chassis
They boot independently and run their own OS
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Clustered Systems
Two or more individual systems coupled together Share storage Linked via a LAN or InfiniBand High availability Clustering
Asymmetric (Hot-standby) Symmetric Parallel clusters: allow multiple hosts to access the
same date on the shared storage
Clustering over a WAN
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Operating-System Structure
Program vs. process/task/job Batch systems Buffering Spooling Multiprogramming
Increasing CPU utilization
Jobs are loaded into memory Scheduling & Memory management Switching at job completion/wait for IO
Time-sharing (Multitasking)
User interaction with the system Switching between users and tasks with high freq.
Switching at job completion/wait for IO/completion of time-slice
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Operating-System Structure
Job scheduling
Selecting a job from the job pool to be loaded into memory
CPU scheduling
Selecting the next ready job to run
Virtual memory
Tries to separate logical memory from physical memory
through swapping Time sharing may require CPU sch., mem. and virtual
- mem. managements, file system, disk management,
protection of resources, job synchronization, deadlock management
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Operating-System Operations
Modern operating systems are interrupt-driven Trap is a software interrupt Dual-Mode operation (through mode bit)
User mode (1) Kernel (Supervisor, System, or Privileged) mode (0)
Privileged instructions
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Privileged Instructions
The instruction to change mode bit I/O instructions Timer management Interrupt (and interrupt vector) management
What would be occurred if it was not privileged?
… Errors violating modes are detected by the
hardware and it will trap to the OS. The trap transfers control through the interrupt vector to the OS.
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Timer
Fixed or variable timer Preventing a program from getting stuck in an
infinite loop
Time sharing
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Operating-System Operations
Process Management Memory Management Storage Management
File-System Mass-Storage Caching I/O Systems