introduction to operating systems chapter 1. cs431 -cotter2 lecture objectives understand the...

Introduction toOperating Systems

Chapter 1

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Lecture Objectives

• Understand the relationship between computing hardware, operating system, and user level applications

• Be able to discuss the different categories of system calls common to Linux or Windows operating systems.

• Discuss how the evolution of computing hardware and the evolution of operating systems have affected each other.

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Basic Computer System Operation

c acheCPU (*N)

device

Instructionsand data

Memory

Instructions

data

I/O R

equest

data

interrupt

DMA

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PC Hardware Review

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CPU Pipelining

Figure 1-7. (a) A three-stage pipeline. (b) A superscalar CPU.

Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639

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Figure 1-8. (a) A quad-core chip with a shared L2 cache. (b) A quad-core chip with separate L2 caches.

Multithreaded and Multicore Chips


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Figure 1-9. A typical memory hierarchy. The numbers are very rough approximations.

Memory (1)


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Questions when dealing with cache:

• When to put a new item into the cache.• Which cache line to put the new item in.• Which item to remove from the cache when a

slot is needed.• Where to put a newly evicted item in the larger

memory.

Memory (2)


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Figure 1-10. Structure of a disk drive.

Disks


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Figure 1-11. (a) The steps in starting an I/O device and getting an interrupt.

I/O Devices


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Interrupt functions

• Most operating systems are interrupt driven

• Interrupt transfers control to interrupt service routine through the interrupt vector

• Save address of interrupted instruction

• Disable interrupts during processing

• A trap is a software generated interrupt

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I/O Structure

• Control returns to user when I/O completes– wait instruction idles CPU– wait loop (contention for memory)– only 1 I/O request outstanding at any time

• Control returns to user without waiting for I/O– system call– device-status table– OS modifies table entry to include interrupt

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Hardware Protection Schemes

• Dual-Mode Operation– user mode– monitor mode / kernel mode

• I/O Protection

• Memory Protection– base register– limit register

• CPU Protection– timer

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Figure 1-12. The structure of a large Pentium system

Buses


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• Processes• Address spaces• Files• Input/Output• Protection• The shell• Evolution repeats itself

• Large memories• Protection hardware• Disks• Virtual memory

Operating System Concepts


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Processes

Figure 1-13. A process tree. Process A created two child processes, B and C. Process B created three child

processes, D, E, and F.


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Figure 1-14. A file system for a university department.

Files (1)


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Figure 1-15. (a) Before mounting, the files on the CD-ROM are not accessible. (b) After mounting, they are part of the file hierarchy.

Files (2)


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Figure 1-16. Two processes connected by a pipe.

Files (3)


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Figure 1-17. The 11 steps in making the system call read(fd, buffer, nbytes).

System Calls


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Figure 1-18. Some of the major POSIX system calls.

System Calls for Process Management


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System Calls for File Management (1)


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System Calls for File Management (2)


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Miscellaneous System Calls


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Figure 1-19. A stripped-down shell.

A Simple Shell


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Figure 1-20. Processes have three segments: text, data, and stack.

Memory Layout


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Figure 1-21. (a) Two directories before linking /usr/jim/memo to ast’s directory. (b) The same directories after linking.

Linking


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Figure 1-22. (a) File system before the mount. (b) File system after the mount.

Mounting


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Figure 1-23. The Win32 API calls that roughly correspond to the UNIX calls of Fig. 1-18.

Windows Win32 API


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Monolithic systems – basic structure:

• A main program that invokes the requested service procedure.

• A set of service procedures that carry out the system calls.

• A set of utility procedures that help the service procedures.

Operating Systems Structure


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Figure 1-24. A simple structuring model for a monolithic system.

Monolithic Systems


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Figure 1-25. Structure of the THE operating system.

Layered Systems


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Figure 1-26. Structure of the MINIX 3 system.

Microkernels


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Figure 1-27. The client-server model over a network.

Client-Server Model


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Virtual Machines

• Pushes the layered concept to the next step

• Treats OS and hardware as though they were both hardware by providing a software (virtual) interface to the OS that is identical to the hardware interface

• OS creates the illusion of several different processes, each executing on its own processor with its own (virtual) memory

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Virtual Machines

• CPU scheduling creates the appearance that each process has its own processor.

• Spooling and a file system can provide “virtual” line printers and “virtual” card readers

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Figure 1-28. The structure of VM/370 with CMS.

Virtual Machines (1)


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Figure 1-29. (a) A type 1 hypervisor. (b) A type 2 hypervisor.

Virtual Machines (2)


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39

JAVA Virtual Machines

Java program

Java program

VM

Java Cmds

Java program

VM

Java Cmds

Java program

VM

Java Cmds

SPARC PowerPC Intel

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Virtual MachineAdvantages / Disadvantages

• Provides complete isolation and protection of resources between processes. (This also can affect the ability to share between processes).

• Provides a good vehicle for reducing system level complexity of IT systems

• Requires hardware support to allow execution of privileged instructions in user mode.

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• The C language• Header files• Large programming projects• The model of run time

The World According to C


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Figure 1-30. The process of compiling C and header files to make an executable.

The Model of Run Time


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Summary

• Overview of Computer Hardware

• Different OS types

• OS Components– Concepts– System Calls– Structure

• OS Programming Language

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Questions:

• What is multi-programming? Why is it important in OSs?

• What is the difference between a system call and a local function call?

• What is the difference between user mode What is the difference between user mode and kernel mode?and kernel mode?

• Why are Virtual Machines becoming popular today in PCs?

• How is the Client / Server model being used today?

introduction to operating systems chapter 1. cs431 -cotter2 lecture objectives understand the...

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modern operating systems

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windows operating systems

process b

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new item

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shared l2 cache