The Big Picture So Far Today: Process Management
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Processes Process States
Processes • A process is a program in execution • Synonyms include job, task, and unit of work • Not surprisingly, then, the parts of a process are precisely the parts of a running program: Program code, sometimes called the text section Program counter (where we are in the code) and other registers (data that CPU instructions can touch directly) Stack — for subroutines and their accompanying data Data section — for statically-allocated entities Heap — for dynamically-allocated entities Process States • Five states in general, with specific operating systems applying their own terminology and some using a finer level of granularity: New — process is being created Running — CPU is executing the process’s instructions Waiting — process is, well, waiting for an event, typically I/O or signal Ready — process is waiting for a processor Terminated — process is done running • See the text for a general state diagram of how a process moves from one state to another The Process Control Block (PCB) • Central data structure for representing a process, a.k.a. task control block • Consists of any information that varies from process to process: process state, program counter, registers, scheduling information, memory management information, accounting information, I/O status • The operating system maintains collections of PCBs to track current processes (typically as linked lists) • System state is saved/loaded to/from PCBs as the CPU goes from process to process; this is called… The Context Switch • Context switch is the technical term for the act -
Chapter 3: Processes
Chapter 3: Processes Operating System Concepts – 9th Edition Silberschatz, Galvin and Gagne ©2013 Chapter 3: Processes Process Concept Process Scheduling Operations on Processes Interprocess Communication Examples of IPC Systems Communication in Client-Server Systems Operating System Concepts – 9th Edition 3.2 Silberschatz, Galvin and Gagne ©2013 Objectives To introduce the notion of a process -- a program in execution, which forms the basis of all computation To describe the various features of processes, including scheduling, creation and termination, and communication To explore interprocess communication using shared memory and message passing To describe communication in client-server systems Operating System Concepts – 9th Edition 3.3 Silberschatz, Galvin and Gagne ©2013 Process Concept An operating system executes a variety of programs: Batch system – jobs Time-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 Multiple parts The program code, also called text section Current activity including program counter, processor registers Stack containing temporary data Function parameters, return addresses, local variables Data section containing global variables Heap containing memory dynamically allocated during run time Operating System Concepts – 9th Edition 3.4 Silberschatz, Galvin and Gagne ©2013 Process Concept (Cont.) Program is passive entity stored on disk (executable -
HP Decset for Openvms Guide to the Module Management System
HP DECset for OpenVMS Guide to the Module Management System Order Number: AA–P119J–TE July 2005 This guide describes the Module Management System (MMS) and explains how to get started using its basic features. Revision/Update Information: This is a revised manual. Operating System Version: OpenVMS I64 Version 8.2 OpenVMS Alpha Version 7.3–2 or 8.2 OpenVMS VAX Version 7.3 Windowing System Version: DECwindows Motif for OpenVMS I64 Version 1.5 DECwindows Motif for OpenVMS Alpha Version 1.3–1 or 1.5 DECwindows Motif for OpenVMS VAX Version 1.2–6 Software Version: HP DECset Version 12.7 for OpenVMS Hewlett-Packard Company Palo Alto, California © Copyright 2005 Hewlett-Packard Development Company, L.P. Confidential computer software. Valid license from HP required for possession, use or copying. Consistent with FAR 12.211 and 12.212, Commercial Computer Software, Computer Software Documentation, and Technical Data for Commercial Items are licensed to the U.S. Government under vendor’s standard commercial license. The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. HP shall not be liable for technical or editorial errors or omissions contained herein. Intel and Itanium are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries. Java is a US trademark of Sun Microsystems, Inc. Microsoft, Windows, and Windows NT are U.S. registered trademarks of Microsoft Corporation. -
CS 450: Operating Systems Sean Wallace <[email protected]>
Deadlock CS 450: Operating Systems Computer Sean Wallace <[email protected]> Science Science deadlock |ˈdedˌläk| noun 1 [ in sing. ] a situation, typically one involving opposing parties, in which no progress can be made: an attempt to break the deadlock. –New Oxford American Dictionary 2 Traffic Gridlock 3 Software Gridlock mutex_A.lock() mutex_B.lock() mutex_B.lock() mutex_A.lock() # critical section # critical section mutex_B.unlock() mutex_B.unlock() mutex_A.unlock() mutex_A.unlock() 4 Necessary Conditions for Deadlock 5 That is, what conditions need to be true (of some system) so that deadlock is possible? (Not the same as causing deadlock!) 6 1. Mutual Exclusion Resources can be held by process in a mutually exclusive manner 7 2. Hold & Wait While holding one resource (in mutex), a process can request another resource 8 3. No Preemption One process can not force another to give up a resource; i.e., releasing is voluntary 9 4. Circular Wait Resource requests and allocations create a cycle in the resource allocation graph 10 Resource Allocation Graphs 11 Process: Resource: Request: Allocation: 12 R1 R2 P1 P2 P3 R3 Circular wait is absent = no deadlock 13 R1 R2 P1 P2 P3 R3 All 4 necessary conditions in place; Deadlock! 14 In a system with only single-instance resources, necessary conditions ⟺ deadlock 15 P3 R1 P1 P2 R2 P2 Cycle without Deadlock! 16 Not practical (or always possible) to detect deadlock using a graph —but convenient to help us reason about things 17 Approaches to Dealing with Deadlock 18 1. Ostrich algorithm (Ignore it and hope it never happens) 2. -
Sched-ITS: an Interactive Tutoring System to Teach CPU Scheduling Concepts in an Operating Systems Course
Wright State University CORE Scholar Browse all Theses and Dissertations Theses and Dissertations 2017 Sched-ITS: An Interactive Tutoring System to Teach CPU Scheduling Concepts in an Operating Systems Course Bharath Kumar Koya Wright State University Follow this and additional works at: https://corescholar.libraries.wright.edu/etd_all Part of the Computer Engineering Commons, and the Computer Sciences Commons Repository Citation Koya, Bharath Kumar, "Sched-ITS: An Interactive Tutoring System to Teach CPU Scheduling Concepts in an Operating Systems Course" (2017). Browse all Theses and Dissertations. 1745. https://corescholar.libraries.wright.edu/etd_all/1745 This Thesis is brought to you for free and open access by the Theses and Dissertations at CORE Scholar. It has been accepted for inclusion in Browse all Theses and Dissertations by an authorized administrator of CORE Scholar. For more information, please contact [email protected]. SCHED – ITS: AN INTERACTIVE TUTORING SYSTEM TO TEACH CPU SCHEDULING CONCEPTS IN AN OPERATING SYSTEMS COURSE A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science By BHARATH KUMAR KOYA B.E, Andhra University, India, 2015 2017 Wright State University WRIGHT STATE UNIVERSITY GRADUATE SCHOOL April 24, 2017 I HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER MY SUPERVISION BY Bharath Kumar Koya ENTITLED SCHED-ITS: An Interactive Tutoring System to Teach CPU Scheduling Concepts in an Operating System Course BE ACCEPTED IN PARTIAL FULFILLMENT OF THE REQIREMENTS FOR THE DEGREE OF Master of Science. _____________________________________ Adam R. Bryant, Ph.D. Thesis Director _____________________________________ Mateen M. Rizki, Ph.D. Chair, Department of Computer Science and Engineering Committee on Final Examination _____________________________________ Adam R. -
Linux-Kernel
linux-kernel #linux- kernel Table of Contents About 1 Chapter 1: Getting started with linux-kernel 2 Remarks 2 Versions 2 Examples 2 Installation or Setup 2 Download extract and enter to the kernel directory 2 Build the dependencies, compile the kernel and modules. 3 Chapter 2: Creation and usage of Kernel Threads 4 Introduction 4 Examples 4 Creation of kernel threads 4 Chapter 3: Event Tracing 6 Examples 6 Tracing I2C Events 6 Chapter 4: Fork System call 7 Examples 7 fork() system call 7 Chapter 5: How to find the right person for help. 9 Introduction 9 Examples 9 Find the "likely" maintainers for the FTDI USB serial converter 9 Chapter 6: Linux Hello World Device driver 10 Examples 10 An empty kernel module 10 Building and running the module 10 Chapter 7: Linux: Named Pipes(FIFO) 12 Examples 12 What is Named Pipe (FIFO) 12 Credits 13 About You can share this PDF with anyone you feel could benefit from it, downloaded the latest version from: linux-kernel It is an unofficial and free linux-kernel ebook created for educational purposes. All the content is extracted from Stack Overflow Documentation, which is written by many hardworking individuals at Stack Overflow. It is neither affiliated with Stack Overflow nor official linux-kernel. The content is released under Creative Commons BY-SA, and the list of contributors to each chapter are provided in the credits section at the end of this book. Images may be copyright of their respective owners unless otherwise specified. All trademarks and registered trademarks are the property of their respective company owners. -
6.087 Practical Programming in C, Lecture 14
Outline Review Inter process communication Signals Fork Pipes FIFO Spotlights 1 6.087 Lecture 14 – January 29, 2010 Review Inter process communication Signals Fork Pipes FIFO Spotlights 2 Review: multithreading • Race conditions • non-determinism in thread order. • can be prevented by synchronization • atomic operations necessary for synchronization • Mutex: Allows a single thread to own it • Semaphores: Generalization of mutex, allows N threads to acquire it at a time. • P(s) : acquires a lock • V(s) : releases lock • sem_init(),sem_destroy() • sem_wait(),sem_trywait(),sem_post() • Other problems: deadlock, starvation 2 Sockets • <sys/socket.h> • enables client-server computing • Client: connect() • Server: bind(),listen(),accept() • I/O: write(),send(),read(),recv() 3 6.087 Lecture 14 – January 29, 2010 Review Inter process communication Signals Fork Pipes FIFO Spotlights 4 Preliminaries • Each process has its own address space. Therefore, individual processes cannot communicate unlike threads. • Interprocess communication: Linux/Unix provides several ways to allow communications • signal • pipes • FIFO queues • shared memory • semaphores • sockets 4 <signals.h> • Unix/Linux allows us to handle exceptions that arise during execution (e.g., interrupt, floating point error, segmentation fault etc.). • A process recieves a signal when such a condition occurs. void (∗signal(int sig,void(∗handler)(int )))( int ) • determines how subsequent signals will be handled. • pre-defined behavior: SIG_DFL (default), SIG_IGN (ignore) • returns the previous handler. 5 <signal.h> Valid signals: SIGABRT abnormal termination SIGFPE floating point error SIGILL illegal instruction SIGINT interrupt SIGSEGV segmentation fault SIGTERM termination request SIGBUS bus error SIGQUIT quit The two signals SIGSTOP,SIGKILL cannot be handled. 6 <signal.h> int raise( int sig) can be used to send signal sig to the program. -
Lecture 4: September 13 4.1 Process State
CMPSCI 377 Operating Systems Fall 2012 Lecture 4: September 13 Lecturer: Prashant Shenoy TA: Sean Barker & Demetre Lavigne 4.1 Process State 4.1.1 Process A process is a dynamic instance of a computer program that is being sequentially executed by a computer system that has the ability to run several computer programs concurrently. A computer program itself is just a passive collection of instructions, while a process is the actual execution of those instructions. Several processes may be associated with the same program; for example, opening up several windows of the same program typically means more than one process is being executed. The state of a process consists of - code for the running program (text segment), its static data, its heap and the heap pointer (HP) where dynamic data is kept, program counter (PC), stack and the stack pointer (SP), value of CPU registers, set of OS resources in use (list of open files etc.), and the current process execution state (new, ready, running etc.). Some state may be stored in registers, such as the program counter. 4.1.2 Process Execution States Processes go through various process states which determine how the process is handled by the operating system kernel. The specific implementations of these states vary in different operating systems, and the names of these states are not standardised, but the general high-level functionality is the same. When a process is first started/created, it is in new state. It needs to wait for the process scheduler (of the operating system) to set its status to "new" and load it into main memory from secondary storage device (such as a hard disk or a CD-ROM). -
Execution Architecture for Real-Time Systems by Ton Kostelijk
Execution Architecture for Real-Time Systems Dr. A.P. Kostelijk (Ton) Version 0.1 Ton Kostelijk - Philips Digital 1 Systems Labs Content • Discussion on You: performance issues • Discussion • Introductory examples • OS: process context switch, process- creation, thread, co-operative / • Various scheduling preemptive multi-tasking, exercises scheduling, EDF, RMS, RMA. • How to design concur- rency / multi-tasking • RMA exercise Version 0.1 Ton Kostelijk - Philips Digital 2 Systems Labs Discussion on performance issues SW HW Version 0.1 Ton Kostelijk - Philips Digital 3 Systems Labs Model: Levels of execution Execution architecture 1. Task and priority assignment Execution architecture SW 2. Algorithms, source code Compiler 3. Machine code, CPU HW arch, settings HW 4. Busses and buffering: data comm. HW arch, settings 5. Device access Version 0.1 Ton Kostelijk - Philips Digital 4 Systems Labs Content • Discussion on You: performance issues • Discussion • Introductory examples • OS: process context switch, process- creation, thread, preemptive • Various scheduling multi-tasking, scheduling, EDF, exercises RMS, RMA. • How to design concur- rency / multi-tasking • RMA exercise Version 0.1 Ton Kostelijk - Philips Digital 5 Systems Labs Example 1: a coffee machine a = place new filter; 1 b = add new coffee; 1 ED c = fill water reservoir; 2 D DL DI d = heat water and pour; 2 D F G PDLQ ^D E F G ` W PDLQ ^F D E G ` W PDLQ ^DBL FBL DBI E FBI G ` W Version 0.1 Ton Kostelijk - Philips Digital 6 Systems Labs Observations • Timing requirements of actions are determined by dependency relations and deadlines. • Hard-coded schedule of actions: + Reliable, easy testable + For small systems might be the best choice. -
Pid T Fork(Void); Description: Fork Creates a Child Process That Differs
pid_t fork(void); Description: fork creates a child process that differs from the parent process only in its PID and PPID, and in the fact that resource utilizations are set to 0. File locks and pending signals are not inherited. Returns: On success, the PID of the child process is returned in the parent's thread of execution, and a 0 is returned in the child's thread of execution. int execve(const char *filename, char *const argv [], char *const envp[]); Description: execve() executes the program pointed to by filename. filename must be either a binary executable, or a script. argv is an array of argument strings passed to the new program. envp is an array of strings, conventionally of the form key=value, which are passed as environment to the new program. Returns: execve() does not return on success, and the text, data, bss, and stack of the calling process are overwritten by that of the program loaded. pid_t wait(int *status); pid_t waitpid(pid_t pid, int *status, int options); Description: The wait function suspends execution of the current process until a child has exited, or until a signal is delivered whose action is to terminate the current process or to call a signal handling function. The waitpid function suspends execution of the current process until a child as specified by the pid argument has exited, or until a signal is delivered whose action is to terminate the current process or to call a signal handling function. If a child has already exited by the time of the call (a so-called \zombie" process), the function returns immediately. -
System Calls & Signals
CS345 OPERATING SYSTEMS System calls & Signals Panagiotis Papadopoulos [email protected] 1 SYSTEM CALL When a program invokes a system call, it is interrupted and the system switches to Kernel space. The Kernel then saves the process execution context (so that it can resume the program later) and determines what is being requested. The Kernel carefully checks that the request is valid and that the process invoking the system call has enough privilege. For instance some system calls can only be called by a user with superuser privilege (often referred to as root). If everything is good, the Kernel processes the request in Kernel Mode and can access the device drivers in charge of controlling the hardware (e.g. reading a character inputted from the keyboard). The Kernel can read and modify the data of the calling process as it has access to memory in User Space (e.g. it can copy the keyboard character into a buffer that the calling process has access to) When the Kernel is done processing the request, it restores the process execution context that was saved when the system call was invoked, and control returns to the calling program which continues executing. 2 SYSTEM CALLS FORK() 3 THE FORK() SYSTEM CALL (1/2) • A process calling fork()spawns a child process. • The child is almost an identical clone of the parent: • Program Text (segment .text) • Stack (ss) • PCB (eg. registers) • Data (segment .data) #include <sys/types.h> #include <unistd.h> pid_t fork(void); 4 THE FORK() SYSTEM CALL (2/2) • The fork()is one of the those system calls, which is called once, but returns twice! Consider a piece of program • After fork()both the parent and the child are .. -
CS415: Systems Programming
CS415: Systems Programming Process Related Systems Call (System, Fork, EXEC) Most of the slides in this lecture are either from or adapted from the slides provided by Dr. Ahmad Barghash Creating processes • Method (1) using system • The system function in the standard C library provides an easy way to execute a command from within a program, much as if the command had been typed into a shell. #include <stdlib.h> int main () { int return_value; return_value = system (“ls -l /”); return return_value; } Creating processes • Method (2) using fork and exec • Linux provides one function, fork, that makes a child process that is an exact copy of its parent process • Linux provides another set of functions, the exec family, that causes a particular process to cease being an instance of one program and to instead become an instance of another program • To spawn a new process, you first use fork to make a copy of the current process. Then you use exec to transform one of these processes into an instance of the program you want to spawn int fork(void) • Description: create a child process • Returns: process ID of the new process int fork(void) parent getpid() : 60 fork() getpid() : 60 getppid() : 59 getppid() : 59 fork_pid : 61 parent fork_pid = fork() child fork() getpid() : 61 getppid() : 60 fork_pid : 0 fork() - Example Using fork to duplicate a program’s process #include <stdio.h> #include <sys/types.h> #include <unistd.h> int main () { pid_t child_pid; printf (“the main program process ID is %d\n”, (int) getpid ()); child_pid = fork (); if (child_pid != 0) { printf (“this is the parent process, with id %d\n”, (int) getpid ()); printf (“the child’s process ID is %d\n”, (int) child_pid); } else printf (“this is the child process, with id %d\n”, (int) getpid ()); return 0; } Contd.