Linux Standard Base Core Module Specification for IA64 2.0.1
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CSE421 Midterm Solutions —SOLUTION SET— 09 Mar 2012
CSE421 Midterm Solutions —SOLUTION SET— 09 Mar 2012 This midterm exam consists of three types of questions: 1. 10 multiple choice questions worth 1 point each. These are drawn directly from lecture slides and intended to be easy. 2. 6 short answer questions worth 5 points each. You can answer as many as you want, but we will give you credit for your best four answers for a total of up to 20 points. You should be able to answer the short answer questions in four or five sentences. 3. 2 long answer questions worth 20 points each. Please answer only one long answer question. If you answer both, we will only grade one. Your answer to the long answer should span a page or two. Please answer each question as clearly and succinctly as possible. Feel free to draw pic- tures or diagrams if they help you to do so. No aids of any kind are permitted. The point value assigned to each question is intended to suggest how to allocate your time. So you should work on a 5 point question for roughly 5 minutes. CSE421 Midterm Solutions 09 Mar 2012 Multiple Choice 1. (10 points) Answer all ten of the following questions. Each is worth one point. (a) In the story that GWA (Geoff) began class with on Monday, March 4th, why was the Harvard student concerned about his grade? p He never attended class. He never arrived at class on time. He usually fell asleep in class. He was using drugs. (b) All of the following are inter-process (IPC) communication mechanisms except p shared files. -
Name Synopsis Description
UTMP(5) Linux Programmer’sManual UTMP(5) NAME utmp, wtmp − login records SYNOPSIS #include <utmp.h> DESCRIPTION The utmp file allows one to discoverinformation about who is currently using the system. There may be more users currently using the system, because not all programs use utmp logging. Warning: utmp must not be writable by the user class "other", because manysystem programs (foolishly) depend on its integrity.You risk faked system logfiles and modifications of system files if you leave utmp writable to anyuser other than the owner and group owner of the file. The file is a sequence of utmp structures, declared as follows in <utmp.h> (note that this is only one of sev- eral definitions around; details depend on the version of libc): /* Values for ut_type field, below */ #define EMPTY 0/*Record does not contain valid info (formerly known as UT_UNKNOWN on Linux) */ #define RUN_LVL 1/*Change in system run-level (see init(8)) */ #define BOOT_TIME 2/*Time of system boot (in ut_tv)*/ #define NEW_TIME 3/*Time after system clock change (in ut_tv)*/ #define OLD_TIME 4/*Time before system clock change (in ut_tv)*/ #define INIT_PROCESS 5/*Process spawned by init(8) */ #define LOGIN_PROCESS 6 /* Session leader process for user login */ #define USER_PROCESS 7/*Normal process */ #define DEAD_PROCESS 8/*Terminated process */ #define ACCOUNTING 9/*Not implemented */ #define UT_LINESIZE 32 #define UT_NAMESIZE 32 #define UT_HOSTSIZE 256 struct exit_status { /* Type for ut_exit, below */ short int e_termination; /* Process termination status */ short int -
Precise Garbage Collection for C
Precise Garbage Collection for C Jon Rafkind Adam Wick John Regehr Matthew Flatt University of Utah Galois, Inc. University of Utah University of Utah [email protected] [email protected] [email protected] mfl[email protected] Abstract no-ops. The resulting program usually runs about as well as before, Magpie is a source-to-source transformation for C programs that but without the ongoing maintenance burden of manual memory enables precise garbage collection, where precise means that inte- management. In our experience, however, conservative GC works gers are not confused with pointers, and the liveness of a pointer poorly for long-running programs, such as a web server, a program- is apparent at the source level. Precise GC is primarily useful for ming environment, or an operating system kernel. For such pro- long-running programs and programs that interact with untrusted grams, conservative GC can trigger unbounded memory use due to components. In particular, we have successfully deployed precise linked lists [Boehm 2002] that manage threads and continuations; GC in the C implementation of a language run-time system that was this problem is usually due to liveness imprecision [Hirzel et al. originally designed to use conservative GC. We also report on our 2002], rather than type imprecision. Furthermore, the programs experience in transforming parts of the Linux kernel to use precise are susceptible to memory-exhaustion attack from malicious code GC instead of manual memory management. (e.g., user programs or untrusted servlets) that might be otherwise restricted through a sandbox [Wick and Flatt 2004]. Categories and Subject Descriptors D.4.2 [Storage Manage- This paper describes our design of and experience with a GC ment]: Garbage Collection for C that is less conservative. -
Man Pages Section 3 Library Interfaces and Headers
man pages section 3: Library Interfaces and Headers Part No: 816–5173–16 September 2010 Copyright © 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. -
Filesystem Hierarchy Standard
Filesystem Hierarchy Standard LSB Workgroup, The Linux Foundation Filesystem Hierarchy Standard LSB Workgroup, The Linux Foundation Version 3.0 Publication date March 19, 2015 Copyright © 2015 The Linux Foundation Copyright © 1994-2004 Daniel Quinlan Copyright © 2001-2004 Paul 'Rusty' Russell Copyright © 2003-2004 Christopher Yeoh Abstract This standard consists of a set of requirements and guidelines for file and directory placement under UNIX-like operating systems. The guidelines are intended to support interoperability of applications, system administration tools, development tools, and scripts as well as greater uniformity of documentation for these systems. All trademarks and copyrights are owned by their owners, unless specifically noted otherwise. Use of a term in this document should not be regarded as affecting the validity of any trademark or service mark. Permission is granted to make and distribute verbatim copies of this standard provided the copyright and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this standard under the conditions for verbatim copying, provided also that the title page is labeled as modified including a reference to the original standard, provided that information on retrieving the original standard is included, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this standard into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the copyright holder. Dedication This release is dedicated to the memory of Christopher Yeoh, a long-time friend and colleague, and one of the original editors of the FHS. -
UNIX Logs Agent User.S Guide
IBM Tivoli Monitoring Version 6.2.3 Fix Pack 1 UNIX Logs Agent User’s Guide SC32-9471-05 IBM Tivoli Monitoring Version 6.2.3 Fix Pack 1 UNIX Logs Agent User’s Guide SC32-9471-05 Note Before using this information and the product it supports, read the information in “Notices” on page 99. This edition applies to version 6.2.3 Fix Pack 1 of the IBM Tivoli Monitoring: UNIX Logs Agent (5724-C04) and to all subsequent releases and modifications until otherwise indicated in new editions. © Copyright IBM Corporation 2005, 2012. US Government Users Restricted Rights – Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Tables ...............v HACMP_join_standby situation ......32 HACMP_network_down situation ......32 Chapter 1. Overview of the Monitoring HACMP_network_down_complete situation . 32 Agent for UNIX Logs .........1 HACMP_network_up situation .......32 HACMP_network_up_complete situation . 32 IBM Tivoli Monitoring overview........1 HACMP_node_down situation .......33 Features of the Monitoring Agent for UNIX Logs . 1 HACMP_node_down_complete situation . 33 New in this release ............2 HACMP_node_down_local situation .....33 Monitoring Agent for UNIX Logs components . 2 HACMP_node_down_local_complete situation . 33 User interface options ...........3 HACMP_node_down_remote situation ....33 HACMP_node_down_rmt_complete situation . 34 Chapter 2. Requirements and HACMP_node_up situation ........34 configuration for the monitoring agent . 5 HACMP_node_up_complete situation ....34 Requirements for the monitoring agent .....6 HACMP_node_up_local situation ......34 Monitoring syslog files on certain AIX 5.3 systems. 8 HACMP_node_up_local_complete situation . 34 Specifying the log files to monitor .......8 HACMP_node_up_remote situation .....35 Customer configuration file ........8 HACMP_node_up_remote_complete situation . 35 Customer configuration file format ......9 HACMP_release_service_addr situation ....35 Syslog daemon configuration file ......10 HACMP_release_takeover_addr situation . -
The Complete Freebsd
The Complete FreeBSD® If you find errors in this book, please report them to Greg Lehey <grog@Free- BSD.org> for inclusion in the errata list. The Complete FreeBSD® Fourth Edition Tenth anniversary version, 24 February 2006 Greg Lehey The Complete FreeBSD® by Greg Lehey <[email protected]> Copyright © 1996, 1997, 1999, 2002, 2003, 2006 by Greg Lehey. This book is licensed under the Creative Commons “Attribution-NonCommercial-ShareAlike 2.5” license. The full text is located at http://creativecommons.org/licenses/by-nc-sa/2.5/legalcode. You are free: • to copy, distribute, display, and perform the work • to make derivative works under the following conditions: • Attribution. You must attribute the work in the manner specified by the author or licensor. • Noncommercial. You may not use this work for commercial purposes. This clause is modified from the original by the provision: You may use this book for commercial purposes if you pay me the sum of USD 20 per copy printed (whether sold or not). You must also agree to allow inspection of printing records and other material necessary to confirm the royalty sums. The purpose of this clause is to make it attractive to negotiate sensible royalties before printing. • Share Alike. If you alter, transform, or build upon this work, you may distribute the resulting work only under a license identical to this one. • For any reuse or distribution, you must make clear to others the license terms of this work. • Any of these conditions can be waived if you get permission from the copyright holder. Your fair use and other rights are in no way affected by the above. -
Part I: Unix Signals
Part I: Unix Signals 1 Stopping a Program What if you run this program? int main () { while (1); printf("bye\n"); return 0; } What happens if you hit Ctl-C? Could you make Ctl-C print ªbyeº before exiting? 2-4 Signals A shell handles Ctl-C by sending the SIGINT signal to a process The sigaction() function can be used to install a signal handler See bye.c and bye2.c 5 Some Other Signals SIGHUP terminal is gone SIGQUIT please quit SIGKILL force quit (cannot handle) SIGSEGV seg fault SIGALRM timer expired SIGPIPE write to pipe with closed read end SIGCHLD child completed 6 Timers Use setitimer() to start a timer See timer.c and timer2.c... 7 Signal Handlers and Races Beware! Ð a signal handler is practically a thread Use sigprocmask() to (un)block signals See timer3.c 8 Part II: Deadlock · Conditions · Prevention · Detection 9 Deadlock is when two or more threads are waiting for an event that can only be generated by these same threads printer->Wait(); disk->Wait(); disk->Wait(); printer->Wait(); // copy from disk // copy from disk // to printer // to printer printer->Signal(); printer->Signal(); disk->Signal(); disk->Signal(); Deadlock can occur anytime threads acquire multiple resources (printers, disks, etc.), perform work, and then release their resources 10 Deadlock 11 Deadlock 12 Deadlock Examples · Linux: In-kernel memory allocator runs out of pages, causing an ªout of memory handlerº to run, which calls a function that tries to allocate a page. · Windows 2000: The OS keeps a pool of ªworker threadsº waiting to do work; one worker thread submits a job to another worker thread, but there are no free worker-thread slots. -
Automatic Handling of Global Variables for Multi-Threaded MPI Programs
Automatic Handling of Global Variables for Multi-threaded MPI Programs Gengbin Zheng, Stas Negara, Celso L. Mendes, Laxmikant V. Kale´ Eduardo R. Rodrigues Department of Computer Science Institute of Informatics University of Illinois at Urbana-Champaign Federal University of Rio Grande do Sul Urbana, IL 61801, USA Porto Alegre, Brazil fgzheng,snegara2,cmendes,[email protected] [email protected] Abstract— necessary to privatize global and static variables to ensure Hybrid programming models, such as MPI combined with the thread-safety of an application. threads, are one of the most efficient ways to write parallel ap- In high-performance computing, one way to exploit multi- plications for current machines comprising multi-socket/multi- core nodes and an interconnection network. Global variables in core platforms is to adopt hybrid programming models that legacy MPI applications, however, present a challenge because combine MPI with threads, where different programming they may be accessed by multiple MPI threads simultaneously. models are used to address issues such as multiple threads Thus, transforming legacy MPI applications to be thread-safe per core, decreasing amount of memory per core, load in order to exploit multi-core architectures requires proper imbalance, etc. When porting legacy MPI applications to handling of global variables. In this paper, we present three approaches to eliminate these hybrid models that involve multiple threads, thread- global variables to ensure thread-safety for an MPI program. safety of the applications needs to be addressed again. These approaches include: (a) a compiler-based refactoring Global variables cause no problem with traditional MPI technique, using a Photran-based tool as an example, which implementations, since each process image contains a sep- automates the source-to-source transformation for programs arate instance of the variable. -
Threading and GUI Issues for R
Threading and GUI Issues for R Luke Tierney School of Statistics University of Minnesota March 5, 2001 Contents 1 Introduction 2 2 Concurrency and Parallelism 2 3 Concurrency and Dynamic State 3 3.1 Options Settings . 3 3.2 User Defined Options . 5 3.3 Devices and Par Settings . 5 3.4 Standard Connections . 6 3.5 The Context Stack . 6 3.5.1 Synchronization . 6 4 GUI Events And Blocking IO 6 4.1 UNIX Issues . 7 4.2 Win32 Issues . 7 4.3 Classic MacOS Issues . 8 4.4 Implementations To Consider . 8 4.5 A Note On Java . 8 4.6 A Strategy for GUI/IO Management . 9 4.7 A Sample Implementation . 9 5 Threads and GUI’s 10 6 Threading Design Space 11 6.1 Parallelism Through HL Threads: The MXM Options . 12 6.2 Light-Weight Threads: The XMX Options . 12 6.3 Multiple OS Threads Running One At A Time: MSS . 14 6.4 Variations on OS Threads . 14 6.5 SMS or MXS: Which To Choose? . 14 7 Light-Weight Thread Implementation 14 1 March 5, 2001 2 8 Other Issues 15 8.1 High-Level GUI Interfaces . 16 8.2 High-Level Thread Interfaces . 16 8.3 High-Level Streams Interfaces . 16 8.4 Completely Random Stuff . 16 1 Introduction This document collects some random thoughts on runtime issues relating to concurrency, threads, GUI’s and the like. Some of this is extracted from recent R-core email threads. I’ve tried to provide lots of references that might be of use. -
KAAPI: a Thread Scheduling Runtime System for Data Flow Computations
KAAPI: A thread scheduling runtime system for data flow computations on cluster of multi-processors Thierry Gautier, Xavier Besseron, Laurent Pigeon INRIA, projet MOAIS LIG, Batiment^ ENSIMAG 51 avenue Jean-Kuntzmann F-38330 Montbonnot St Martin, France [email protected], [email protected], [email protected] ABSTRACT among the processors. In the work-stealing scheduling [7], The high availability of multiprocessor clusters for com- each processor gets its own stack implemented by a deque puter science seems to be very attractive to the engineer of frames. When a thread is created, a new frame is ini- because, at a first level, such computers aggregate high per- tialized and pushed at the bottom of the deque. When a formances. Nevertheless, obtaining peak performances on processor become idle, it tries to steal work from a victim irregular applications such as computer algebra problems re- processor with a non-empty deque; then it takes the top- mains a challenging problem. The delay to access memory is most frame (the least recently pushed frame) and places it non uniform and the irregularity of computations requires to in its own deque which is linked to the victim deque. use scheduling algorithms in order to automatically balance Such scheduling has been proven to be efficient for fully- the workload among the processors. strict multithreaded computations [7, 12] while requiring a This paper focuses on the runtime support implementa- bounded memory space with respect to a depth first sequen- tion to exploit with great efficiency the computation re- tial execution [8, 29]. sources of a multiprocessor cluster. -
Linux Standard Base Core Specification 2.0.1
Linux Standard Base Core Specification 2.0 .1 Linux Standard Base Core Specification 2.0 .1 Copyright © 2004 Free Standards Group Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License". Portions of the text are copyrighted by the following parties: • The Regents of the University of California • Free Software Foundation • Ian F. Darwin • Paul Vixie • BSDI (now Wind River) • Andrew G Morgan • Jean-loup Gailly and Mark Adler • Massachusetts Institute of Technology These excerpts are being used in accordance with their respective licenses. Linux is a trademark of Linus Torvalds. UNIX a registered trademark of the Open Group in the United States and other countries. LSB is a trademark of the Free Standards Group in the USA and other countries. AMD is a trademark of Advanced Micro Devices, Inc. Intel and Itanium are registered trademarks and Intel386 is a trademarks of Intel Corporation. OpenGL is a registered trademark of Silicon Graphics, Inc. Specification Introduction Specification Introduction Table of Contents Foreword .......................................................................................................................................................................i Introduction ...............................................................................................................................................................