DOCSLIB.ORG

An Overview of Security in the Freebsd Kernel 131 Dr

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

AsiaBSDCon 2014 Proceedings March 13-16, 2014 Tokyo, Japan Copyright c 2014 BSD Research. All rights reserved. Unauthorized republication is prohibited. Published in Japan, March 2014 INDEX P1A: Bold, fast optimizing linker for BSD — Luba Tang P1B: Visualizing Unix: Graphing bhyve, ZFS and PF with Graphite 007 Michael Dexter P2A: LLVM in the FreeBSD Toolchain 013 David Chisnall P2B: NPF - progress and perspective 021 Mindaugas Rasiukevicius K1: OpenZFS: a Community of Open Source ZFS Developers 027 Matthew Ahrens K2: Bambi Meets Godzilla: They Elope 033 Eric Allman P3A: Snapshots, Replication, and Boot-Environments—How new ZFS utilities are changing FreeBSD & PC-BSD 045 Kris Moore P3B: Netmap as a core networking technology 055 Luigi Rizzo, Giuseppe Lettieri, and Michio Honda P4A: ZFS for the Masses: Management Tools Provided by the PC-BSD and FreeNAS Projects 065 Dru Lavigne P4B: OpenBGPD turns 10 years - Design, Implementation, Lessons learned 077 Henning Brauer P5A: Introduction to FreeNAS development 083 John Hixson P5B: VXLAN and Cloud-based networking with OpenBSD 091 Reyk Floeter INDEX P6A: Nested Paging in bhyve 097 Neel Natu and Peter Grehan P6B: Developing CPE Routers based on NetBSD: Fifteen Years of SEIL 107 Masanobu SAITOH and Hiroki SUENAGA P7A: Deploying FreeBSD systems with Foreman and mfsBSD 115 Martin Matuška P7B: Implementation and Modification for CPE Routers: Filter Rule Optimization, IPsec Interface and Ethernet Switch 119 Masanobu SAITOH and Hiroki SUENAGA K3: Modifying the FreeBSD kernel Netflix streaming servers — Scott Long K4: An Overview of Security in the FreeBSD Kernel 131 Dr. Marshall Kirk McKusick P8A: Transparent Superpages for FreeBSD on ARM 151 Zbigniew Bodek P8B: Carve your NetBSD 165 Pierre Pronchery and Guillaume Lasmayous P9A: How FreeBSD Boots: a soft-core MIPS perspective 179 Brooks Davis, Robert Norton, Jonathan Woodruff, and Robert N. M. Watson P9B: Adapting OSX to the enterprise 187 Jos Jansen P10A: Analysis of BSD Associate Exam Results 199 Jim Brown Visualizing Unix: Graphing bhyve, ZFS and PF with Graphite Michael Dexter <[email protected]> AsiaBSDCon 2014, Tokyo, Japan "Silence is golden", or so goes the classic Unix tenet and the result is that a traditional Unix system provides us only a command prompt while performing its most demanding tasks. While this is perfectly correct behavior, it provides the operator few insights into the strain that a given system may be experiencing or if the system is behaving unexpectedly. In this study we will explore a strategy for institutionally visualizing Unix system activity using collectd, its site-specific alternatives, Graphite, DTrace and FreeBSD. We have chosen FreeBSD because it includes a trifecta of Unix innovations: the bhyve hypervisor, the PF packet filter and the ZFS file system. While each of these tools provides its own facilities for displaying performance metrics, they collectively present a challenge to quantify their interaction. Existing Facilities Complementing the familiar yet verbose top(1), tcpdump(1) and gstat(8) commands, bhyve, PF and ZFS each have their own dedicated tools for interactively and noninteractively displaying their activity metrics. The first of these, the bhyve hypervisor, includes the most limited quantification facility of the set. The /usr/sbin/bhyvectl --get-stats --vm=<vm name> command provides a summary of virtual machine (VM) operation with an emphasis on its kernel resource utilization but few with insights into its relative performance to the host. The PF packet filter includes the pflog(4) logging interface for use with tcpdump(1) but the output is consistent with standard tcpdump(1) behavior, providing literally a view of active network connections. tcpdump(1) is complemented by other in-base tools such as netstat(1) but none make any effort to visualize the activity of a given network interface. Finally, the ZFS file system benefits from in-base tools such as gstat(8) which introduce visual aids such as color coding of file system input/output operations and can be further complimented with tools like sysutils/zfs-stats but each nonetheless provides a simplistic summary of file system activity and performance. Environment While the subject of this study is the bhyve hypervisor itself, bhyve will also serve as the primary environment for the study. This choice was made because of bhyve's indistinguishable host and VM performance with CPU-intensive tasks, precluding the use of a more-familiar virtualization technology such as FreeBSD jail(8). Virtual machines will be used for not only as participant hosts but can also be used for primary hosts as the statistics collection and graphing host. The choice of the bhyve hypervisor allows for this study to be conducted on FreeBSD 10.0 or later, PC-BSD 10.0 or later and its sister distribution TrueOS. Testing Methodology While the bhyve hypervisor is fully functional with the included vmrun.sh script found in /usr/share/examples/bhyve/, this study will elect to use the vmrc system found a bhyve.org/tools/vmrc/. vmrc is a virtual machine run command script that facilitates the full provisioning (formatting and OS installation) and management (loading, booting, stopping) of bhyve virtual machines. vmrc usage is as follows: 7 VM configuration files are located in /usr/local/vm/ and can be installed with the included install.sh script. vmrc usage is displayed with '/usr/local/etc/rc.d/vm' and a VM is provisioned with '/usr/local/etc/rc.d/vm provision vm0' which corresponds to the vm0 configuration file found at /usr/local/etc/rc.d/vm/vm0/vm0.conf . # /usr/local/etc/rc.d/vm Usage: /usr/local/etc/rc.d/vm [fast|force|one|quiet](start|stop|restart|rcvar|enabled|attach|boot |debug|delete|destroy|fetch|format|grub|install|iso|jail|load|mount |provision|status|umount) vmrc's behavior is documented in the included instructions.txt file. For our purposes, each VM will be simply provisioned with the ‘provision’ directive and loaded and booted with the ‘start’ directive. This study will require at a minimum one or more participant hosts that will be analyzed and optionally a VM for telemetry collection and graphing. Graphite is a numeric time-series data and graphing system built in the Python scripting language and is best documented at https://graphite.readthedocs.org . Legacy and independent documentation sources exist but they vary in reliability and are rarely BSD Unix-oriented. The countless opportunities to customize a Graphite graphing deployments has resulted in a myriad of often site-specific documentation. For our purposes we will demonstrate a minimalistic “stock” Graphite installation that uses default settings whenever possible. Graphite Components Graphite is comprised of the graphite-web Django web framework “project” that performs all telemetry presentation tasks, the carbon telemetry collection daemon (scheduled to be replaced by the ceres daemon) and the whisper round-robin storage system. Host activity telemetry from one or more hosts is sent to the carbon daemon which in turn stores it in whisper, which retains or discards telemetry data according to pre-determined criteria, resulting in a fixed-size database after all criteria have been applied. The whisper storage system is modular and can be replaced with alternative stores and the carbon telemetry collection daemon is data source-agnostic. carbon is often supplied host telemetry using the collectd or statsd system statistics collection daemons but such data can also be provided with a myriad of other tools given that the telemetry data format is very simple: <host.data.name> <statistic> <UET timestamp> which is fed into port 2003 of the carbon host using TCP or UDP. graphite-web in turn presents the host telemetry stored in whisper in a user-friendly manner by default on port 8080 of the graphite-web host which is in turn often served via an established http daemon such as lighttpd, Apache or Nginx via the Python-based Web Server Gateway Interface (WSGI). Complexity is the enemy of reliability… …or installability for that matter. The operator will quickly find that the myriad of possible Graphite configurations will greatly complicate the installation and operation of Graphite with most 8 documentation being of a site-specific and advanced-user nature. This study will mercifully provide a minimalistic “default” configuration but in doing so will provide one that is highly user- customizable in exchange for a negligible performance impact. The result is a “Unix” style configuration if you will that leverages familiar Unix conventions and established programmability. Example host or virtual machine telemetry collection and transmission script #!/bin/sh host=$( uname -n ) # Used to distinguish the source within carbon interval=3 # Sampling interval in seconds destination=localhost # The carbon host port=2003 # The default carbon port while :; do # Operate continuously until terminated externally sleep $interval timestamp=$( date +%s ) # Average load within last minute from uptime(1) load=$( uptime | grep -ohe 'load average[s:][: ].*' | \ awk '{ print $3 }' | sed 's/,$//') echo "${host}.cpu.load $load $timestamp" | \ socat - udp-sendto:$destination:$port echo "Sent: ${host}.cpu.load $load $timestamp" # Debug # IOPS from gstat(8) iops=$( gstat -b | grep ada0 | head -1 | \ awk '{print $2}' ) echo "${host}.ada0.iops $iops $timestamp" | \ socat - udp-sendto:$destination:$port echo "Sent: ${host}.ada0.iops $iops $timestamp” done Example bhyve virtual machine telemetry syntax for the
Recommended publications
  • The Design and Implementation of Multiprocessor Support for an Industrial Operating System Kernel

    The Design and Implementation of Multiprocessor Support for an Industrial Operating System Kernel

    Blekinge Institute of Technology Research Report 2005:06 The Design and Implementation of Multiprocessor Support for an Industrial Operating System Kernel Simon Kågström Håkan Grahn Lars Lundberg Department of Systems and Software School of Engineering Blekinge Institute of Technology The Design and Implementation of Multiprocessor Support for an Industrial Operating System Kernel Simon Kågström, Håkan Grahn, and Lars Lundberg Department of Systems and Software Engineering School of Engineering Blekinge Institute of Technology P.O. Box 520, SE-372 25 Ronneby, Sweden {ska, hgr, llu}@bth.se Abstract The ongoing transition from uniprocessor to multiprocessor computers requires support from the op- erating system kernel. Although many general-purpose multiprocessor operating systems exist, there is a large number of specialized operating systems which require porting in order to work on multipro- cessors. In this paper we describe the multiprocessor port of a cluster operating system kernel from a producer of industrial systems. Our initial implementation uses a giant locking scheme that serializes kernel execution. We also employed a method in which CPU-local variables are placed in a special sec- tion mapped to per-CPU physical memory pages. The giant lock and CPU-local section allowed us to implement an initial working version with only minor changes to the original code, although the giant lock and kernel-bound applications limit the performance of our multiprocessor port. Finally, we also discuss experiences from the implementation. 1 Introduction A current trend in the computer industry is the transition from uniprocessors to various kinds of multipro- cessors, also for desktop and embeddedsystems. Apart from traditional SMP systems, many manufacturers are now presenting chip multiprocessors or simultaneous multithreaded CPUs [9, 15, 16] which allow more efficient use of chip area.
  • Red Hat Satellite 6.7 Provisioning Guide

    Red Hat Satellite 6.7 Provisioning Guide

    Red Hat Satellite 6.7 Provisioning Guide A guide to provisioning physical and virtual hosts on Red Hat Satellite Servers. Last Updated: 2021-05-14 Red Hat Satellite 6.7 Provisioning Guide A guide to provisioning physical and virtual hosts on Red Hat Satellite Servers. Red Hat Satellite Documentation Team [email protected] Legal Notice Copyright © 2021 Red Hat, Inc. The text of and illustrations in this document are licensed by Red Hat under a Creative Commons Attribution–Share Alike 3.0 Unported license ("CC-BY-SA"). An explanation of CC-BY-SA is available at http://creativecommons.org/licenses/by-sa/3.0/ . In accordance with CC-BY-SA, if you distribute this document or an adaptation of it, you must provide the URL for the original version. Red Hat, as the licensor of this document, waives the right to enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent permitted by applicable law. Red Hat, Red Hat Enterprise Linux, the Shadowman logo, the Red Hat logo, JBoss, OpenShift, Fedora, the Infinity logo, and RHCE are trademarks of Red Hat, Inc., registered in the United States and other countries. Linux ® is the registered trademark of Linus Torvalds in the United States and other countries. Java ® is a registered trademark of Oracle and/or its affiliates. XFS ® is a trademark of Silicon Graphics International Corp. or its subsidiaries in the United States and/or other countries. MySQL ® is a registered trademark of MySQL AB in the United States, the European Union and other countries.
  • Katalog Elektronskih Knjiga

    Katalog Elektronskih Knjiga

    KATALOG ELEKTRONSKIH KNJIGA Br Autor Naziv Godina ISBN Str. Porijeklo izdavanja 1 Peter Kent Pay Per Click Search 2006 0-471-74594-3 130 Kupovina Engine Marketing for Dummies 2 Terry Large Access 1 2007 Internet Freeware 3 Kevin Smith Excel Lassons & Tutorials 2004 Internet Freeware 4 Terry Michael Photografy Tutorials 2006 Internet Freeware Janine Peterson Phil Pivnick 5 Jake Ludington Converting Vinyl LPs 2003 Internet Freeware to CD 6 Allen Wyatt Cleaning Windows XP 2004 0-7645-7311-X Poklon for Dummies 7 Peter Kent Sarch Engine Optimization 2006 0-4717-5441-2 Kupovina for Dummies 8 Terry Large Access 2 2007 Internet Freeware 9 Dirk Dupon How to write, create, 2005 Internet Freeware promote and sell E-books on the Internet 10 Chayden Bates eBook Marketing 2000 Internet Freeware Explained 11 Kevin Sinclair How To Choose A 1999 Internet Freeware Homebased Bussines 12 Bob McElwain 101 Newbie-Frendly Tips 2001 Internet Freeware 13 Windows Basics 2004 Poklon 14 Michael Abrash Zen of Graphic 2005 Poklon Programming, 2. izdanje 15 13 Hot Internet 2000 Internet Freeware Moneymaking Methods 16 K. Williams The Complete HTML 1998 Poklon Teacher 17 C. Darwin On the Origin of Species Internet Freeware 2/175 Br Autor Naziv Godina ISBN Str. Porijeklo izdavanja 18 C. Darwin The Variation of Animals Internet Freeware 19 Bruce Eckel Thinking in C++, Vol 1 2000 Internet Freeware 20 Bruce Eckel Thinking in C++, Vol 2 2000 Internet Freeware 21 James Parton Captains of Industry 1890 399 Internet Freeware 22 Bruno R. Preiss Data Structures and 1998 Internet
  • BSD Magazine

    BSD Magazine

    FREENAS MINI FREENAS STORAGE APPLIANCE CERTIFIED IT SAVES YOUR LIFE. STORAGE HOW IMPORTANT IS YOUR DATA? With over six million downloads, As one of the leaders in the storage industry, you FreeNAS is undisputedly the most know that you’re getting the best combination of hardware designed for optimal performance Years of family photos. Your entire music popular storage operating system and movie collection. Office documents with FreeNAS. Contact us today for a FREE Risk in the world. you’ve put hours of work into. Backups for Elimination Consultation with one of our FreeNAS experts. Remember, every purchase directly supports every computer you own. We ask again, how Sure, you could build your own FreeNAS system: the FreeNAS project so we can continue adding important is your data? research every hardware option, order all the features and improvements to the software for years parts, wait for everything to ship and arrive, vent at to come. And really - why would you buy a FreeNAS customer service because it hasn’t, and finally build it server from anyone else? NOW IMAGINE LOSING IT ALL yourself while hoping everything fits - only to install the software and discover that the system you spent Losing one bit - that’s all it takes. One single bit, and days agonizing over isn’t even compatible. Or... your file is gone. The worst part? You won’t know until you MAKE IT EASY ON YOURSELF absolutely need that file again. Example of one-bit corruption As the sponsors and lead developers of the FreeNAS project, iXsystems has combined over 20 years of THE SOLUTION hardware experience with our FreeNAS expertise to The Mini boasts these state-of-the- The FreeNAS Mini has emerged as the clear choice to bring you FreeNAS Certified Storage.We make it art features: save your digital life.
  • Advancing Mac OS X Rootkit Detecron

    Advancing Mac OS X Rootkit Detecron

    Advancing Mac OS X Rootkit Detec4on Andrew Case (@attrc) Volatility Foundation Golden G. Richard III (@nolaforensix) University of New Orleans 2 hot research areas State of Affairs more established Live Forensics and Tradional Storage Memory Analysis Forensics Digital Forensics Reverse Engineering Incident Response Increasingly encompasses all the others Copyright 2015 by Andrew Case and Golden G. Richard III 3 Where’s the Evidence? Files and Filesystem Applica4on Windows Deleted Files metadata metadata registry Print spool Hibernaon Temp files Log files files files Browser Network Slack space Swap files caches traces RAM: OS and app data Volale Evidence structures Copyright 2015 by Andrew Case and Golden G. Richard III 4 Volale Evidence 1 011 01 1 0 1 111 0 11 0 1 0 1 0 10 0 1 0 1 1 1 0 0 1 0 1 1 0 0 1 Copyright 2015 by Andrew Case and Golden G. Richard III 5 Awesomeness Progression: File Carving Can carve Chaos: files, but More can't Faster Almost not very accurate Hurray! carve files well Tools Manual File type Fragmentaon, appear, MulDthreading, hex editor aware damned but have beer design stuff carving, et al spinning disks! issues Images: hLps://easiersaidblogdotcom.files.wordpress.com/2013/02/hot_dogger.jpg hLp://cdn.bigbangfish.com/555/Cow/Cow-6.jpg, hLp://f.tqn.com/y/bbq/1/W/U/i/Big_green_egg_large.jpg hLp://i5.walmarDmages.com/dfw/dce07b8c-bb22/k2-_95ea6c25-e9aa-418e-a3a2-8e48e62a9d2e.v1.jpg Copyright 2015 by Andrew Case and Golden G. Richard III 6 Awesomeness Progression: Memory Forensics Pioneering Chaos: More, efforts Beyond run more, show great Windows ?? strings? more promise pt_finder et al More aenDon Manual, Mac, … awesome but to malware, run strings, Linux, BSD liLle context limited filling in the gaps funcDonality Images: hLps://s-media-cache-ak0.pinimg.com/736x/75/5a/37/755a37727586c57a19d42caa650d242e.jpg,, hLp://img.photobucket.com/albums/v136/Hell2Pay77/SS-trucks.jpg hLp://skateandannoy.com/wp-content/uploads/2007/12/sportsbars.jpg, hLp://gainesvillescene.com/wp-content/uploads/2013/03/dog-longboard.jpg Copyright 2015 by Andrew Case and Golden G.
  • Mac OS X Server Administrator's Guide

    Mac OS X Server Administrator's Guide

    034-9285.S4AdminPDF 6/27/02 2:07 PM Page 1 Mac OS X Server Administrator’s Guide K Apple Computer, Inc. © 2002 Apple Computer, Inc. All rights reserved. Under the copyright laws, this publication may not be copied, in whole or in part, without the written consent of Apple. The Apple logo is a trademark of Apple Computer, 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, AppleScript, AppleShare, AppleTalk, ColorSync, FireWire, Keychain, Mac, Macintosh, Power Macintosh, QuickTime, Sherlock, and WebObjects are trademarks of Apple Computer, Inc., registered in the U.S. and other countries. AirPort, Extensions Manager, Finder, iMac, and Power Mac are trademarks of Apple Computer, Inc. Adobe and PostScript are trademarks of Adobe Systems Incorporated. Java and all Java-based trademarks and logos are trademarks or registered trademarks of Sun Microsystems, Inc. in the U.S. and other countries. Netscape Navigator is a trademark of Netscape Communications Corporation. RealAudio is a trademark of Progressive Networks, Inc. © 1995–2001 The Apache Group. All rights reserved. UNIX is a registered trademark in the United States and other countries, licensed exclusively through X/Open Company, Ltd. 062-9285/7-26-02 LL9285.Book Page 3 Tuesday, June 25, 2002 3:59 PM Contents Preface How to Use This Guide 39 What’s Included
  • Jitk: a Trustworthy In-Kernel Interpreter Infrastructure

    Jitk: a Trustworthy In-Kernel Interpreter Infrastructure

    Jitk: A trustworthy in-kernel interpreter infrastructure Xi Wang, David Lazar, Nickolai Zeldovich, Adam Chlipala, Zachary Tatlock MIT and University of Washington Modern OSes run untrusted user code in kernel In-kernel interpreters - Seccomp: sandboxing (Linux) - BPF: packet filtering - INET_DIAG: socket monitoring - Dtrace: instrumentation Critical to overall system security - Any interpreter bugs are serious! 2/30 Many bugs have been found in interpreters Kernel space bugs - Control flow errors: incorrect jump offset, ... - Arithmetic errors: incorrect result, ... - Memory errors: buffer overflow, ... - Information leak: uninitialized read Kernel-user interface bugs - Incorrect encoding/decoding User space bugs - Incorrect input generated by tools/libraries Some have security consequences: CVE-2014-2889, ... See our paper for a case study of bugs 3/30 How to get rid of all these bugs at once? Theorem proving can help kill all these bugs seL4: provably correct microkernel [SOSP'09] CompCert: provably correct C compiler [CACM'09] This talk: Jitk - Provably correct interpreter for running untrusted user code - Drop-in replacement for Linux's seccomp - Built using Coq proof assistant + CompCert 5/30 Theorem proving: overview specification proof implementation Proof is machine-checkable: Coq proof assistant Proof: correct specification correct implementation Specification should be much simpler than implementation 6/30 Challenges What is the specification? How to translate systems properties into proofs? How to extract a running
  • Programmer's Guide

    Programmer's Guide

    Programmer’s Guide Release 2.2.0 January 16, 2016 CONTENTS 1 Introduction 1 1.1 Documentation Roadmap...............................1 1.2 Related Publications..................................2 2 Overview 3 2.1 Development Environment..............................3 2.2 Environment Abstraction Layer............................4 2.3 Core Components...................................4 2.4 Ethernet* Poll Mode Driver Architecture.......................6 2.5 Packet Forwarding Algorithm Support........................6 2.6 librte_net........................................6 3 Environment Abstraction Layer7 3.1 EAL in a Linux-userland Execution Environment..................7 3.2 Memory Segments and Memory Zones (memzone)................ 11 3.3 Multiple pthread.................................... 12 3.4 Malloc.......................................... 14 4 Ring Library 19 4.1 References for Ring Implementation in FreeBSD*................. 20 4.2 Lockless Ring Buffer in Linux*............................ 20 4.3 Additional Features.................................. 20 4.4 Use Cases....................................... 21 4.5 Anatomy of a Ring Buffer............................... 21 4.6 References....................................... 28 5 Mempool Library 31 5.1 Cookies......................................... 31 5.2 Stats.......................................... 31 5.3 Memory Alignment Constraints............................ 31 5.4 Local Cache...................................... 32 5.5 Use Cases....................................... 33 6
  • Chapter 1. Origins of Mac OS X

    Chapter 1. Origins of Mac OS X

    1 Chapter 1. Origins of Mac OS X "Most ideas come from previous ideas." Alan Curtis Kay The Mac OS X operating system represents a rather successful coming together of paradigms, ideologies, and technologies that have often resisted each other in the past. A good example is the cordial relationship that exists between the command-line and graphical interfaces in Mac OS X. The system is a result of the trials and tribulations of Apple and NeXT, as well as their user and developer communities. Mac OS X exemplifies how a capable system can result from the direct or indirect efforts of corporations, academic and research communities, the Open Source and Free Software movements, and, of course, individuals. Apple has been around since 1976, and many accounts of its history have been told. If the story of Apple as a company is fascinating, so is the technical history of Apple's operating systems. In this chapter,[1] we will trace the history of Mac OS X, discussing several technologies whose confluence eventually led to the modern-day Apple operating system. [1] This book's accompanying web site (www.osxbook.com) provides a more detailed technical history of all of Apple's operating systems. 1 2 2 1 1.1. Apple's Quest for the[2] Operating System [2] Whereas the word "the" is used here to designate prominence and desirability, it is an interesting coincidence that "THE" was the name of a multiprogramming system described by Edsger W. Dijkstra in a 1968 paper. It was March 1988. The Macintosh had been around for four years.
  • The Qosbox: Quantitative Service Differentiation in BSD Routers∗

    The Qosbox: Quantitative Service Differentiation in BSD Routers∗

    The QoSbox: Quantitative Service Differentiation in BSD Routers∗ Nicolas Christin Jorg¨ Liebeherr Information Networking Institute and The Edward S. Rogers Sr. Department of CyLab Japan Electrical and Computer Engineering Carnegie Mellon University University of Toronto 1-3-3-17 Higashikawasaki-cho 10 King’s College Road Chuo-ku, Kobe 650-0044, Japan Toronto, ON M5S 3G4, Canada [email protected] [email protected] Abstract We describe the design and implementation of the QoSbox, a configurable IP router that provides per-hop service differentiation on loss, delays and throughput to classes of traffic. The novel aspects of the QoSbox are that (1) the QoSbox does not rely on any external component (e.g., no traffic shaping and no admission control) to provide the desired service differentiation, but instead, (2) dynamically adapts packet forwarding and dropping decisions as a function of the instantaneous traffic arrivals and allows for temporary relaxation of some service objectives; also, (3) the QoSbox can enforce both absolute and proportional service differentiation on queuing delays, loss rates, and throughput at the same time. We focus on a publicly available implementation of the QoSbox in BSD-based PC-routers. We evaluate our implementation in a testbed of BSD routers over a FastEthernet network, and we sketch how the QoSbox can be implemented in high speed architectures. Keywords: Quality-of-Service Implementations, Service Differentiation, PC-Routers, BSD, High-Speed Networks. ∗Most of this work was done while both authors were with the University of Virginia. This work was supported in part by the National Science Foundation through grants ANI-9730103 and ANI-0085955.
  • Types of LMS Deployment & Common Features

    Types of LMS Deployment & Common Features

    Types of LMS Deployment & Common Features Daisyane Barreto, Amy Rottmann, & Salena Rabidoux In cooking, you have many different types of tools you can use to make a meal. For example, you have mixers, measuring cups, cutting boards, and so many other tools. Each tool is designed to meet the needs of the cooker and serve a specific purpose in the cooking process. An LMS is not different in that sense. There are several types of LMSs in the market being used for educational as well as training purposes, and one of the most difficult choices for organizations and institutions to make is deciding the type of LMS to select based on deployment or license (Pappas, 2014). Of course, many other factors (e.g., pricing, support, additional features, and others) must be considered and weighed in this decision. Still, the cost combined with financial and technical requirements are still the main focus when selecting an LMS (Croitoru & Dinu, 2016). Indeed, it is important to analyze and examine the type of LMS deployment because of its influence in the overall cost as well as other relevant requirements that can inform the decision about an LMS. There are two main types of LMS deployment you need to be familiar with: (1) proprietary, and (2) open-source. Within those two solutions, there are two other distinct categories to be considered: (a) Software as a Service (SaaS) or cloud-based system and (b) Installed LMS. In order to determine what type of LMS is beneficial to an organization or institution, a clear understanding of the advantages and disadvantages of each solution must be reviewed.
  • Filesystem Performance on Freebsd

    Filesystem Performance on Freebsd

    Filesystem Performance on FreeBSD Kris Kennaway [email protected] BSDCan 2006, Ottawa, May 12 Introduction ● Filesystem performance has many aspects ● No single metric for quantifying it ● I will focus on aspects that are relevant for my workloads (concurrent package building) ● The main relevant filesystem workloads seem to be – Concurrent tarball extraction – Recursive filesystem traversals ● Aim: determine relative performance of FreeBSD 4.x, 5.x and 6.x on these workloads – Overall performance and SMP scaling – Evaluate results of multi-year kernel locking strategy as it relates to these workloads Outline ● SMP architectural differences between 4/5/6.x ● Test methodology ● Hardware used ● Parallel tarball extraction test – Disk array and memory disk ● Scaling beyond 4 CPUs ● Recursive filesystem traversal test ● Conclusions & future work SMP Architectural Overview ● FreeBSD 4.x; rudimentary SMP support – Giant kernel lock restricts kernel access to one process at a time – SPL model; interrupts may still be processed in parallel ● FreeBSD 5.x; aim towards greater scalability – Giant-locked to begin with; then finer-grained locking pushdown ● FreeBSD 5.3; VM Giant-free ● FreeBSD 5.4; network stack Giant-free (mostly) ● Many other subsystems/drivers also locked – Interrupts as kernel threads; compete for common locks (if any) with everything else ● FreeBSD 6.x; – Consolidation; further pushdown; payoff! – VFS subsystem, UFS filesystem Giant-free FreeBSD versions ● FreeBSD 4.11-STABLE (11/2005) – Needed for amr driver fixes after 4.11-RELEASE ● FreeBSD 5.4-STABLE (11/05) – No patches needed ● FreeBSD 6.0-STABLE (11/05) – patches: ● Locking reworked in amr driver by Scott Long for better performance ● All relevant changes merged into FreeBSD 6.1 – A kernel panic was encountered at very high I/O loads ● Also fixed in 6.1 Test aims and Methodology ● Want to measure – overall performance difference between FreeBSD branches under varying (concurrent process I/O) loads – scaling to multiple CPUs ● Avoid saturating hardware resources (e.g.