welcome to cmpe003 personal computers: hardware and software dr. chane fullmer fall 2002 uc santa...

Welcome to CMPE003 Personal

Computers: Hardware and

SoftwareDr. Chane FullmerDr. Chane Fullmer

Fall 2002Fall 2002

UC Santa CruzUC Santa Cruz

September 27, 2002 2

Assignments

Details on the class web page: http://www.soe.ucsc.edu/classes/cmpe003/Fall02/

TAs Dyng Au Dat Nguyen

Sections Monday – 9 -11AM, SS 1 #135 Tuesday/Thursday – 11 – 12PM, JBE #109 Friday – 9 – 11AM, JBE #109


1st HomeworkDue Today by 11:59PM

NOTE: This homework must be completed successfully to

continue in this class If this homework is not received by the due date,

you will be dropped from the class No adds will be allowed after this due date

-- no exceptions

Due Today……Must be turned in TODAY by 11:59 PM


2nd HomeworkDue October 4, 2002

Web Search Exercise See class web page for details http://www.soe.ucsc.edu/classes/cmpe003/Fall02/


Midterm #1

Friday – October 11 Chapters 1 – 5 ~50 questions Multiple choice

Bring scantron number F-1712-ERI-L (big & pink) Bring your student ID

Required to take exam

OPERATING SYSTEMSSoftware in the Background

Chapter 2

Part B

Resource Allocation


Objectives of Chapter 2 Describe the functions of an Operating System Explain the basics of a personal computer operating system Describe the advantages of a graphical operating system Differentiate among different operating systems Explain the need for network operating systems

Describe the methods of resource allocation on large computers Be able to describe the differences among multiprocessing, multiprogramming, and timesharing Explain the principles of memory management List several functions typically performed by utility programs


Operating SystemHidden Software

Definition – provides access to all resources Kernel

Manages the operating system Memory resident Loads set of programs that lies between applications

software and the hardware Fundamental software that controls non-resident portions of

the OS as needed Booting – Loads the kernel into memory


Functions of OS Manage the computer’s resources

CPU Memory Disk drives Printers

Establish a user interface

Executes and provides services for applications software

Carries out all input and output operations


What is an OS?

Machine/resource manager.

Physical Devices

MicroarchitectureInstruction Set Architecture

Operating System

Utilities, Editors, etc.

Hardware

Application programs


Large Computer OSs

Used by many people at once OS works “behind the scenes” so users

can share resources OS must control

Who gets access to resources What keeps the programs from different users

from getting mixed up with one another


Resource Allocation

Resource – hardware or software that is needed to complete a task

Resource Allocation – assigning computer resources to certain programs

Resource De-allocation – releasing resources when a task is complete


Deadlocks

Shared data/resource may lead to deadlock: processes get “stuck”.

Example: v is using r1 and requests r2; w is using r2 and requests r1.

wv

r1 r2


Allocating the CPU

One CPU Multiprogramming (aka Multitasking)

Event-driven Timesharing

More than one CPU Multiprocessing – multiple CPUs can run

several programs simultaneously SMP – Symmetrical Multi-Processing


Multiprogramming

One CPU Concurrent execution of two or more

processes Several processes open at once Only one process can receive the attention of

the CPU at any given moment Effective because CPU speeds are many

times faster than input/output speeds


Event-driven Multiprogramming

One program receives the attention of the CPU

Its processing will be interrupted based upon events in the program

When processing needs to be temporarily suspended, an interrupt is generated

This is a signal to the operating system to evaluate the cause of the interrupt and determine who should now have CPU time


Event-driven Multiprogramming Example

Two programs are running – Payroll and Inventory Management

Payroll needs to read an employee record

Payroll generates an interrupt to read from the disk

Normal processing is temporarily suspended

The CPU looks at the interrupt and initiates the read operation on the disk drive

While waiting for the read to complete, the CPU begins processing the Inventory Management program


Event-driven Multiprogramming Example

When the disk read operation is complete, another interrupt is generated

Normal processing is temporarily suspended

The CPU looks at the interrupt and determines its cause (read the data in from the disk drive for the Payroll program)

The CPU will either continue processing the Inventory Management program or return to the Payroll program depending upon their priority


Time-sharing Multiprogramming

One program receives the attention of the CPU

A small fraction of CPU time is allocated to the program

The time slice ends

The CPU begins processing a different program

Response time can vary based upon the number of users on the system


Sharing Memory

Program must be in memory to be executed

Problems Programs compete for space May have a very large program Memory space for each program must not

overlap


Memory Management

The process of providing separate memory space to programs

Memory Protection keeps one program from interfering with another


Memory ManagementMethods

Partitions or regions

Foreground and background

Virtual storage (virtual memory)


Partitions or Regions

Divide memory into sections (ie, partitions)

The partition must accommodate the largest possible program

Problem May cause wasted memory space


Foreground and Background Programs are placed in either Foreground or

Background

Programs in Foreground have priority for CPU time

While performing read / write operations for the Foreground program, the CPU gives time to a program in Background

Programs are placed in a holding queue while waiting to run


Virtual StorageVirtual Memory

Uses concept of Paging

Divide the program into equal-size pieces (pages)

Store each piece in equal-size memory spaces (page frames)

Typical size is 2KB or 4KB

Create an index to each page and store in a Page Table


Paging Process

A portion of the program is placed in memory

The remainder is on disk

Sections on disk will be brought into memory as needed (one page at a time)




Problem -- Thrashing A large portion of CPU time is spent swapping the

correct page and bringing it into memory Solution

Run fewer programs concurrently Add memory Program design

“working set” size – number of pages required in memory for program to run


Memory Protection

Keeps one program from straying into another Confines each program to certain defined

limits in memory Why needed

Possible for one program to destroy or modify another by transferring to the wrong memory location

May cause destruction of data Action if assigned memory space is violated

Termination of executing program


Sharing Storage

Several users need to access the same disk pack One wants to write Another wants to read

OS keeps track of the I/O requests

OS processes I/O requests in order received


Sharing Printing Resources

Print resources are shared between active programs

Printouts are generated in pieces as the CPU gives each concurrent program some time

Problem The current program may generate a few print lines The CPU moves to the next program The second program may generate a few print lines,

etc.


Sharing Printing Resources

Result Printout is worthless as it contains a few lines

from several programs

Solution – Spooling Each program thinks it is writing to the printer The program actually writes to the hard disk When the program is complete, the file on the

hard disk is sent to the printer


Additional Printing Problem

Printers are slow compared to the CPU speed

Solution The CPU writing to the disk The program completes quicker


Utility Programs

Come with System Software Handle special needs Perform secondary chores Do not need to be memory resident


Functions of Utility programs File manager – provide access to lists of stored files Backup and Restore – make duplicate copies of

important files and return the copy to the hard drive if needed

File compression – reduces the amount of disk space required by a file

Disk defragmenter – reorganize files so they are stored contiguously on disk providing for faster access

Device drivers – convert operating system instructions into commands that are known to a specific device


Next Week….

Chapter 3 (Monday)“Applications Software: Getting the Work Done”

Chapter 4 (Wednesday/Friday)“The Central Processing unit: What Goes on

Inside the Computer”

welcome to cmpe003 personal computers: hardware and software dr. chane fullmer fall 2002 uc santa...

Documents

memory slide

pm slide

complete slide

exam slide

b resource allocation

wv r1r2 slide

resources os

computer resources