linux software architecture
DESCRIPTION
complete software concrete architecture of linuxTRANSCRIPT
A PAPER PRESENTATION ON
SOFTWARE ARCHITECTURE OF LINUX
WHAT IS INSIDE
1 Introduction
2 Need of the study of Software Architecture
3 System Structure4 Subsystem Inspection5 Future Work6 References
INTRODUCTION
Linus B. Trovalds wrote the Linux Kernel in 1991.
Free and Open SourceA Unix compatible systemOriginally developed to run on the Intel
80386
Need for the Software Architecture StudyEnhance communication among stakeholders
of the systemSupport for earlier design decisions.Understand transferable abstraction of a
systemSoftware maintenanceExploit the FOSS utilities. To extend, remove,
change,modify functionality of an existing system.
Linux System Structure
Criticism-“Linux kernel is useless by itself,it participates as one layer in the overall system.”
Within the kernel layer Linux has 5 major subsystems.
Process SchedulerMemory ManagerVirtual File SystemNetwork interfaceInter process communication
Sub System InspectionProcess Scheduler
Sub System Inspection - Process SchedulerIt is the heart of Linux Operating SystemFunctions: Allows processes to make new copies.SchedulingInterrupt HandlingLoading, Executing and Terminating of
processes.Timer ManagementSupport for Dynamically loaded modules.
Process Scheduler Dependencies
Sub System Inspection –Memory ManagerProvides:Large address spaceProtectionMemory mappingFair access to Physical memoryShared MemoryMemory Manager abstracts details of all hardware
platforms into one common interface. It maps virtual addresses to physical memory addresses.
It also swaps out processes to allow system to execute processes that use more physical memory than available on the system.
Daemon threads
Memory Manager Dependencies
Subsystem Inspection: Virtual File SystemLinux supports:Multiple hardware devicesMultiple logical File SystemMultiple Executable FormatsHomogenity PerformanceSafetySecurity
The FS of Linux has 2 conceptual layers 1. Device Driver Layer
2. Virtual File systemAdd new Device Driver by simply implementing the
abstract interface,Use of Buffer Cache for optimized Performance.Data Transfer can takes place by1.Polling 2.DMA 3.InterruptsTo support Virtual FS Linux has inodes.It makes all
files appear the same to other Linux subsystems
Subsystem Inspection: Virtual File System
VFS Dependencies
Subsystem Inspection:Inter Process Communication
Concurrent Execution of processes for
*Resource Sharing
*Synchronization
*Exchange of dataLinux provides following forms of IPC
-Signals
-Wait Queues
-File Locks
-Pipes and Named PipesSystem VIPC:
->Semaphore ->Message Queues ->Shared Memory
Interprocess Communication Dependencies
Linux supports network connections between machines and socket communication model.2 types of sockets are identified
-BSD sockets -INET sockets BSD abstracts the communication details to a
common interface. This provides greater portability Linux provides two transfer layer protocols
UDP TCP
INET sits on top of both IP and Transport Protocol.
Subsystem Inspection-Network Interface
Subsystem Inspection-Network InterfaceThree types of connections-Serial Line connections-Parallel Line connections-Ethernet connectionsAn address Resolver (ARP)is responsible for
converting the IP addresses into physical ones. This is necessary as sockets deal with IP addresses which cannot be directly used by hardware devices.
Subsystem Inspection-Network Interface
ConclusionLinux has since been ported to more computer hardware
platforms than any other operating system. It is a leading operating system on servers and other big iron
systems such as mainframe computers and supercomputers more than 90% of today's 500 fastest supercomputers run some variant of Linux .
Linux also runs on embedded systems such as mobile phones, tablet computers, network routers, televisions and video game consoles the Android system in wide use on mobile devices is built on the Linux kernel.
Typically Linux is packaged in a format known as a Linux distribution for desktop and server use. Some popular mainstream Linux distributions include Debian , Fedora and openSUSE.
Future WorkConceptual Architecture shows few dependencies among the components than concrete architectureThe PBS tools should be adjusted to handle the Linux source structure. The conceptual and concrete architectures we have presented should be refined through discussions with the Linux developer community. After refinement, the two models can be compared using the Reflexion model [Murphy 1995].
References[Balasubramanian 1993]
Balasubramanian, K. and Johnson D.: "Linux Memory Management Overview," The Linux Kernel Hacker’s Guide,
http://www.redhat.com:8080/hypernews/get/memory/memory.html
[Tanuan 1998]
Tanuan,M.: "An Introduction to the Linux Operating System Architecture", http://www.grad.math.uwaterloo.ca/~mcta
Sahun Siddiqi,Meyer Tanaun,Ivan Bowman:
“Concrete Architecture of Linux”
LINUX- powerful. open source. secure