Chapter 3: Processesturgaybilgin/2015-2016-guz/opsys/cen302_ch3.pdfOperating System Concepts with...

Chapter 3: Processes

Process ConceptProcess SchedulingOperations on ProcessesInterprocess CommunicationExamples of IPC SystemsCommunication in Client-Server Systems

Process Concept

An operating system executes a variety of programs:Batch system – jobsTime-shared systems – user programs or tasks

Textbook uses the terms job and process almost interchangeably

Process – a program in execution; process execution must progress in sequential fashion

A process includes:program counter stackdata section

Process in Memory

Process State

As a process executes, it changes statenew: The process is being createdrunning: Instructions are being executedwaiting: The process is waiting for some event to occurready: The process is waiting to be assigned to a processorterminated: The process has finished execution

Diagram of Process State

Process Control Block (PCB)

Information associated with each process

Process stateProgram counterCPU registersCPU scheduling informationMemory-management informationAccounting informationI/O status information

Process Control Block (PCB)

CPU Switch From Process to Process

Process Scheduling Queues

Job queue – set of all processes in the system

Ready queue – set of all processes residing in main memory, ready and waiting to execute

Device queues – set of processes waiting for an I/O device

Processes migrate among the various queues

Ready Queue And Various I/O Device Queues

Representation of Process Scheduling

Schedulers

Long-term scheduler (or job scheduler) – selects which processes should be brought into the ready queue

Short-term scheduler (or CPU scheduler) – selects which process should be executed next and allocates CPU

Schedulers (Cont.)

Short-term scheduler is invoked very frequently (milliseconds) ⇒(must be fast)

Long-term scheduler is invoked very infrequently (seconds, minutes) ⇒ (may be slow)

Context Switch

When CPU switches to another process, the system must save the state of the old process and load the saved state for the new process via a context switch

Context of a process represented in the PCB

Context-switch time is overhead; the system does no useful work while switching

Time dependent on hardware support

Process Creation

Parent process create children processes, which, in turn create other processes, forming a tree of processes

Generally, process identified and managed via a process identifier (pid)

Parent and children share all resourcesChildren share subset of parent’s resourcesParent and child share no resources

ExecutionParent and children execute concurrentlyParent waits until children terminate

Resource sharing: 3 possibility

Process Creation (Cont.)

Address spaceChild duplicate of parentChild has a program loaded into it

UNIX examplesfork system call creates new processexec system call used after a fork to replace the process’ memory space with a new program

Process Creation

C Program Forking Separate Process

int main(){pid_t pid;

/* fork another process */pid = fork();if (pid < 0) { /* error occurred */

fprintf(stderr, "Fork Failed");exit(-1);

}else if (pid == 0) { /* child process */

execlp("/bin/ls", "ls", NULL);}else { /* parent process */

/* parent will wait for the child to complete */wait (NULL);printf ("Child Complete");exit(0);

Process Creation in POSIX

Process Creation in Win32

Process Termination

Process executes last statement and asks the operating system todelete it (exit)

Output data from child to parent (via wait)Process’ resources are deallocated by operating system

Parent may terminate execution of children processes (abort)Child has exceeded allocated resourcesTask assigned to child is no longer requiredIf parent is exiting

Some operating system do not allow child to continue if its parent terminates

– All children terminated - cascading termination

Interprocess Communication

Processes within a system may be independent or cooperatingCooperating process can affect or be affected by other processes, including sharing dataReasons for cooperating processes:

Information sharingComputation speedupModularity

Cooperating processes need interprocess communication (IPC)Two models of IPC

Shared memoryMessage passing

Communications Models

Producer-Consumer Problem

Paradigm for cooperating processes, producer process produces information that is consumed by a consumer process

unbounded-buffer places no practical limit on the size of the buffer. The consumer may have to wait for new items,but the producer can always produce new items.

bounded-buffer assumes that there is a fixed buffer size.In this case,the consumer must wait if the buffer is empty, and the producer must wait if the buffer is full.

Interprocess Communication –Message Passing

Mechanism for processes to communicate and to synchronize their actionsMessage system – processes communicate with each other without resorting to shared variablesIPC facility provides two operations:

send(message) – message size fixed or variable receive(message)

If P and Q wish to communicate, they need to:establish a communication link between themexchange messages via send/receive

Direct Communication

Processes must name each other explicitly:send (P, message) – send a message to process Preceive(Q, message) – receive a message from process Q

Properties of communication linkLinks are established automaticallyA link is associated with exactly one pair of communicating processesBetween each pair there exists exactly one linkThe link may be unidirectional, but is usually bi-directional

Indirect Communication

Messages are directed and received from mailboxes (also referredto as ports)

Each mailbox has a unique idProcesses can communicate only if they share a mailbox

Properties of communication linkLink established only if processes share a common mailboxA link may be associated with many processesLink may be unidirectional or bi-directional

Indirect Communication

Operationscreate a new mailboxsend and receive messages through mailboxdestroy a mailbox

Primitives are defined as:send(A, message) – send a message to mailbox Areceive(A, message) – receive a message from mailbox A

Synchronization

Message passing may be either blocking or non-blocking

Blocking is considered synchronousBlocking send has the sender block until the message is received

Non-blocking is considered asynchronousNon-blocking send has the sender send the message and continue

Communications in Client-Server Systems

Sockets

Remote Procedure Call (Remote Method Invocation -RMI- in Java)

Sockets

A socket is defined as an endpoint for communication

Concatenation of IP address and port

The socket 161.25.19.8:1625 refers to port 1625 on host 161.25.19.8

Communication consists between a pair of sockets

Socket Communication

Socket Communication in Java

Remote Method InvocationRemote Method Invocation (RMI) is a Java mechanism similar to RPCs

RMI allows a Java program on one machine to invoke a method on aremote object

RMI registry

End of Chapter 3

Chapter 3: Processesturgaybilgin/2015-2016-guz/opsys/cen302_ch3.pdfOperating System Concepts with...

Documents

Operating/Safety Instructions Consignes de …mdm.boschwebservices.com/files/5280_Manual r143893v5.pdfOperating/Safety Instructions Consignes de fonctionnement/sécurité Instrucciones

OptimaTM CNG Fueling Dispenser - Kraus Globalkrausglobal.com/wp-content/uploads/optimabrochure2017june19.pdfoperating parameters thereby maximizing station performance. Fleet managers

Software Performance Tuning Project Flake Prepared by: Meni Orenbach Roman Kaplan Advisors: Zvika Guz Kobi Gottlieb

Operating Manual - Altronicsdownload.altronics.com.au/files/instructions_A4585.pdfOperating Manual A 4585 Zone Paging System ... Manufactured in Australia By Altronic Distributors

Understanding OpSys Perf Metrics - Application … · 2 Understanding OpSys Perf Metrics © 2013 Progresswiz informatique Why Are You Here? ... AIX & Linux: nmon • Get rid of that

Internetworking - jupiter.plymouth.edujupiter.plymouth.edu/~wjt/OpSys/CS-APP/L10-internetworking.pdf · – 2 – CS 4310 – Computer Operating Systems A Client-Server TransactionA

obtained in eighteen normal subjects (Adams, Garlick, Guz, Murphy

Operating System Principles: Memory Management – …lasr.cs.ucla.edu/classes/111_fall16/slides/Lecture_6.pdfOperating System Principles: Memory Management – Swapping, Paging, and

Chapter 8: Memory Management - e-tahtam.comturgaybilgin/2015-2016-guz/opsys/week6/cen3… · Chapter 8: Memory Management. Operating System Concepts with Java – 8 th Edition 8.4

Opsys MW Microplate Washer - Aspect Scientific...Opsys MW Microplate Washer The Opsys MW is an economical, full-featured 96-well microplate strip washer. An excellent choice for many

Synchronization with eventcounts and sequencers - …bill/cs515/Eventcounts_Sequencers_Reed_Kanodia_79.pdfoperating systems, particularly: Brinch-Hansen's RC 4000 system, Multics,

Chapter 6: CPU Schedulingturgaybilgin/2015-2016-guz/opsys/btu/ch6.pdf · Operating System Concepts Essentials –2nd Edition 6.8 Silberschatz, Galvin and Gagne ©2013 FCFS Scheduling

OpSys Slides 1

Operating Instructions - PLICSRADIO T61 - wireless ...manual_en).pdfOperating Instructions PLICSRADIO T61 Wireless Gateway wireless emitting unit (single channel) Signal conditioning

LHCb HCAL PMT problems HAMAMATSU studies 1 Yu. Guz

MuhFak Guz Vize - 2610 ev - Muhendislik-Anasayfamuhendislik.cbu.edu.tr/db_images/file/2016_2017/guz/MuhFak_Guz_Vize... · CELAL BAYAR ÜN İVERS İTES İ / MÜHEND İSL İK FAKÜLTES

Introduction to Embedded and Ubiquitous Systemsjupiter.plymouth.edu/~wjt/OpSys/EmbeddedSystems1.pdf · 3 ICS212 WQ05 (Dutt) Introduction 5 Reading Materials zRecommended Books Peter

ECAL and HCAL status 1Yu. Guz 2014/11/26. TED shots, 24-Nov 2Yu. Guz 2014/11/26

OPERATING INSTRUCTIONS AND SERVICE …support.everbrite.com/products/downloads/scoreboards/.../3351.pdfOPERATING INSTRUCTIONS AND SERVICE MANUAL BASEBALL SCOREBOARD MODEL MP-3351

Speeding up VirtualDub Presented by: Shmuel Habari Advisor: Zvika Guz Software Systems Lab Technion