Processes Operating Systems Grado En Informática
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Parallel Programming in Unix, Many Programs Run in at the Same Time
parallelism parallel programming! to perform a number of tasks simultaneously! these can be calculations, or data transfer or…! In Unix, many programs run in at the same time handling various tasks! we like multitasking…! we don’t like waiting… "1 simplest way: FORK() Each process has a process ID called PID.! After a fork() call, ! there will be a second process with another PID which we call the child. ! The first process, will also continue to exist and to execute commands, we call it the mother. "2 fork() example #include <stdio.h> // printf, stderr, fprintf! ! #include <sys/types.h> // pid_t ! } // end of child! #include <unistd.h> // _exit, fork! else ! #include <stdlib.h> // exit ! { ! #include <errno.h> // errno! ! ! /* If fork() returns a positive number, we int main(void)! are in the parent process! {! * (the fork return value is the PID of the pid_t pid;! newly created child process)! pid = fork();! */! ! int i;! if (pid == -1) {! for (i = 0; i < 10; i++)! fprintf(stderr, "can't fork, error %d\n", {! errno);! printf("parent: %d\n", i);! exit(EXIT_FAILURE);! sleep(1);! }! }! ! exit(0);! if (pid == 0) {! }// end of parent! /* Child process:! ! * If fork() returns 0, it is the child return 0;! process.! } */! int j;! for (j = 0; j < 15; j++) {! printf("child: %d\n", j);! sleep(1);! }! _exit(0); /* Note that we do not use exit() */! !3 why not to fork fork() system call is the easiest way of branching out to do 2 tasks concurrently. BUT" it creates a separate address space such that the child process has an exact copy of all the memory segments of the parent process. -
Freebsd-And-Git.Pdf
FreeBSD and Git Ed Maste - FreeBSD Vendor Summit 2018 Purpose ● History and Context - ensure we’re starting from the same reference ● Identify next steps for more effective use / integration with Git / GitHub ● Understand what needs to be resolved for any future decision on Git as the primary repository Version control history ● CVS ○ 1993-2012 ● Subversion ○ src/ May 31 2008, r179447 ○ doc/www May 19, 2012 r38821 ○ ports July 14, 2012 r300894 ● Perforce ○ 2001-2018 ● Hg Mirror ● Git Mirror ○ 2011- Subversion Repositories svnsync repo svn Subversion & Git Repositories today svn2git git push svnsync git svn repo svn git github Repositories Today fork repo / Freebsd Downstream svn github github Repositories Today fork repo / Freebsd Downstream svn github github “Git is not a Version Control System” phk@ missive, reproduced at https://blog.feld.me/posts/2018/01/git-is-not-revision-control/ Subversion vs. Git: Myths and Facts https://svnvsgit.com/ “Git has a number of advantages in the popularity race, none of which are really to do with the technology” https://chapmanworld.com/2018/08/25/why-im-now-using-both-git-and-subversion-for-one-project/ 10 things I hate about Git https://stevebennett.me/2012/02/24/10-things-i-hate-about-git Git popularity Nobody uses Subversion anymore False. A myth. Despite all the marketing buzz related to Git, such notable open source projects as FreeBSD and LLVM continue to use Subversion as the main version control system. About 47% of other open source projects use Subversion too (while only 38% are on Git). (2016) https://svnvsgit.com/ Git popularity (2018) Git UI/UX Yes, it’s a mess. -
Getting Started With... Berkeley Software for UNIX† on the VAX‡ (The Third Berkeley Software Distribution)
Getting started with... Berkeley Software for UNIX† on the VAX‡ (The third Berkeley Software Distribution) A package of software for UNIX developed at the Computer Science Division of the University of California at Berkeley is installed on our system. This package includes a new version of the operating sys- tem kernel which supports a virtual memory, demand-paged environment. While the kernel change should be transparent to most programs, there are some things you should know if you plan to run large programs to optimize their performance in a virtual memory environment. There are also a number of other new pro- grams which are now installed on our machine; the more important of these are described below. Documentation The new software is described in two new volumes of documentation. The first is a new version of volume 1 of the UNIX programmers manual which has integrated manual pages for the distributed software and incorporates changes to the system made while introducing the virtual memory facility. The second volume of documentation is numbered volume 2c, of which this paper is a section. This volume contains papers about programs which are in the distribution package. Where are the programs? Most new programs from Berkeley reside in the directory /usr/ucb. A major exception is the C shell, csh, which lives in /bin. We will later describe how you can arrange for the programs in the distribution to be part of your normal working environment. Making use of the Virtual Memory With a virtual memory system, it is no longer necessary for running programs to be fully resident in memory. -
Version 7.8-Systemd
Linux From Scratch Version 7.8-systemd Created by Gerard Beekmans Edited by Douglas R. Reno Linux From Scratch: Version 7.8-systemd by Created by Gerard Beekmans and Edited by Douglas R. Reno Copyright © 1999-2015 Gerard Beekmans Copyright © 1999-2015, Gerard Beekmans All rights reserved. This book is licensed under a Creative Commons License. Computer instructions may be extracted from the book under the MIT License. Linux® is a registered trademark of Linus Torvalds. Linux From Scratch - Version 7.8-systemd Table of Contents Preface .......................................................................................................................................................................... vii i. Foreword ............................................................................................................................................................. vii ii. Audience ............................................................................................................................................................ vii iii. LFS Target Architectures ................................................................................................................................ viii iv. LFS and Standards ............................................................................................................................................ ix v. Rationale for Packages in the Book .................................................................................................................... x vi. Prerequisites -
CS 350 Operating Systems Spring 2021
CS 350 Operating Systems Spring 2021 4. Process II Discussion 1: Question? • Why do UNIX OSes use the combination of “fork() + exec()” to create a new process (from a program)? • Can we directly call exec() to create a new process? Or, do you have better ideas/designs for creating a new process? • Hints: To answer this question: think about the possible advantages of this solution. Fork Parent process Child process Exec New program image in execution 2 Discussion 1: Background • Motived by the UNIX shell • $ echo “Hello world!” • $ Hello world! • shell figures out where in the file system the executable “echo” resides, calls fork() to create a new child process, calls exec() to run the command, and then waits for the command to complete by calling wait(). • You can see that you can use fork(), exec() and wait() to implement a shell program – our project! • But what is the benefit of separating fork() and exec() in creating a new process? 3 Discussion 1: Case study • The following program implements the command: • $ wc p3.c > p4.output # wc counts the word number in p3.c • # the result is redirected to p4.output Close default standard output (to terminal) open file p4.output 4 Discussion 1: Case study • $ wc p3.c # wc outputs the result to the default standard output, specified by STDOUT_FILENO • By default, STDOUT_FILENO points to the terminal output. • However, we close this default standard output → close(STDOUT_FILENO ); • Then, when we open the file “p4.output” • A file descriptor will be assigned to this file • UNIX systems start looking for free file descriptors from the beginning of the file descriptor table (i.e., at zero). -
Oracle Solaris Security for Developers Guide • September 2010 Contents
Oracle® Solaris Security for Developers Guide Part No: 816–4863–16 September 2010 Copyright © 2004, 2010, Oracle and/or its affiliates. All rights reserved. This software and related documentation are provided under a license agreement containing restrictions on use and disclosure and are protected by intellectual property laws. Except as expressly permitted in your license agreement or allowed by law, you may not use, copy, reproduce, translate, broadcast, modify, license, transmit, distribute, exhibit, perform, publish, or display any part, in any form, or by any means. Reverse engineering, disassembly, or decompilation of this software, unless required by law for interoperability, is prohibited. The information contained herein is subject to change without notice and is not warranted to be error-free. If you find any errors, please report them to us in writing. If this is software or related software documentation that is delivered to the U.S. Government or anyone licensing it on behalf of the U.S. Government, the following notice is applicable: U.S. GOVERNMENT RIGHTS Programs, software, databases, and related documentation and technical data delivered to U.S. Government customers are “commercial computer software” or “commercial technical data” pursuant to the applicable Federal Acquisition Regulation and agency-specific supplemental regulations. As such, the use, duplication, disclosure, modification, and adaptation shall be subject to the restrictions and license terms setforth in the applicable Government contract, and, to the extent applicable by the terms of the Government contract, the additional rights set forth in FAR 52.227-19, Commercial Computer Software License (December 2007). Oracle America, Inc., 500 Oracle Parkway, Redwood City, CA 94065. -
The Dragonflybsd Operating System
1 The DragonFlyBSD Operating System Jeffrey M. Hsu, Member, FreeBSD and DragonFlyBSD directories with slightly over 8 million lines of code, 2 million Abstract— The DragonFlyBSD operating system is a fork of of which are in the kernel. the highly successful FreeBSD operating system. Its goals are to The project has a number of resources available to the maintain the high quality and performance of the FreeBSD 4 public, including an on-line CVS repository with mirror sites, branch, while exploiting new concepts to further improve accessible through the web as well as the cvsup service, performance and stability. In this paper, we discuss the motivation for a new BSD operating system, new concepts being mailing list forums, and a bug submission system. explored in the BSD context, the software infrastructure put in place to explore these concepts, and their application to the III. MOTIVATION network subsystem in particular. A. Technical Goals Index Terms— Message passing, Multiprocessing, Network The DragonFlyBSD operating system has several long- operating systems, Protocols, System software. range technical goals that it hopes to accomplish within the next few years. The first goal is to add lightweight threads to the BSD kernel. These threads are lightweight in the sense I. INTRODUCTION that, while user processes have an associated thread and a HE DragonFlyBSD operating system is a fork of the process context, kernel processes are pure threads with no T highly successful FreeBSD operating system. Its goals are process context. The threading model makes several to maintain the high quality and performance of the FreeBSD guarantees with respect to scheduling to ensure high 4 branch, while exploring new concepts to further improve performance and simplify reasoning about concurrency. -
Making Processes
Making Processes • Topics • Process creation from the user level: • fork, execvp, wait, waitpid • Learning Objectives: • Explain how processes are created • Create new processes, synchronize with them, and communicate exit codes back to the forking process. • Start building a simple shell. 11/8/16 CS61 Fall 2016 1 Recall how we create processes: fork #include <unistd.h> pid_t ret_pid; ret_pid = fork(); switch (ret_pid){ case 0: /* I am the child. */ break; case -1: /* Something bad happened. */ break; default: /* * I am the parent and my child’s * pid is ret_pid. */ break; } 11/8/16 CS61 Fall 2016 2 But what good are two identical processes? • So fork let us create a new process, but it’s identical to the original. That might not be very handy. • Enter exec (and friends): The exec family of functions replaces the current process image with a new process image. • exec is the original/traditional API • execve is the modern day (more efficient) implementation. • There are a pile of functions, all of which ultimately invoke execve; we will focus on execvp (which is recommended for Assignment 5). • If execvp returns, then it was unsuccessful and will return -1 and set errno. • If successful, execvp does not return, because it is off and running as a new process. • Arguments: • file: Name of a file to be executed • args: Null-terminated argument vector; the first entry of which is (by convention) the file name associated with the file being executed. 11/8/16 CS61 Fall 2016 3 Programming with Exec #include <unistd.h> #include <errno.h> #include <stdio.h> pid_t ret_pid; ret_pid = fork(); switch (ret_pid){ case 0: /* I am the child. -
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. -
Open Directory Administration for Version 10.5 Leopard Second Edition
Mac OS X Server Open Directory Administration For Version 10.5 Leopard Second Edition Apple Inc. © 2008 Apple Inc. All rights reserved. The owner or authorized user of a valid copy of Mac OS X Server software may reproduce this publication for the purpose of learning to use such software. No part of this publication may be reproduced or transmitted for commercial purposes, such as selling copies of this publication or for providing paid-for support services. Every effort has been made to make sure that the information in this manual is correct. Apple Inc., is not responsible for printing or clerical errors. Apple 1 Infinite Loop Cupertino CA 95014-2084 www.apple.com The Apple logo is a trademark of Apple Inc., registered in the U.S. and other countries. Use of the “keyboard” Apple logo (Option-Shift-K) for commercial purposes without the prior written consent of Apple may constitute trademark infringement and unfair competition in violation of federal and state laws. Apple, the Apple logo, iCal, iChat, Leopard, Mac, Macintosh, QuickTime, Xgrid, and Xserve are trademarks of Apple Inc., registered in the U.S. and other countries. Finder is a trademark of Apple Inc. Adobe and PostScript are trademarks of Adobe Systems Incorporated. UNIX is a registered trademark of The Open Group. Other company and product names mentioned herein are trademarks of their respective companies. Mention of third-party products is for informational purposes only and constitutes neither an endorsement nor a recommendation. Apple assumes no responsibility with regard to the performance or use of these products. -
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). -
Deploying-Zones-11Gr2-Supercluster
An Oracle Technical White Paper November 2012 Best Practices for Deploying Oracle Solaris Zones with Oracle Database 11g on SPARC SuperCluster Best Practices for Deploying Oracle Solaris Zones with Oracle Database 11g on SPARC SuperCluster Introduction ....................................................................................... 1 SPARC SuperCluster Technologies for Database Consolidation ....... 2 SPARC T4-4 Domains in the SPARC SuperCluster ...................... 3 Database Services Within the SPARC SuperCluster ..................... 3 Database Consolidation on the SPARC SuperCluster ................... 4 Oracle Solaris Zones on the SPARC SuperCluster ........................ 4 Best Practices for Deploying Oracle Database 11g Using Oracle Solaris Zones .................................................................................... 6 Choosing the Number of Database Domains ................................. 6 Oracle Solaris Zones ..................................................................... 7 ZFS File System .......................................................................... 11 Zone Deployment Using the ssc_exavm Tool ............................ 11 Operating System Tunable Parameters ....................................... 12 Database Grid Configuration ....................................................... 14 Oracle RAC Configuration ........................................................... 19 Securing the Databases in SPARC SuperCluster ........................ 20 Example Database Consolidation Scenarios