Modern Operating Systems

MODERN OPERATING SYSTEMSRIYAZ P A16, S2 MTECH CSEMACE1CONTENTSIntroductionMicrokernel Architecture MultithreadingSymmetric Multiprocessing Distributed Operating SystemsObject-oriented designConclusion

5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam2INTRODUCTIONNew design elements were introduced recentlyIn response to new hardware developmentmultiprocessor machineshigh-speed networksfaster processors and larger memoryIn response to new software needsmultimedia applicationsInternet and Web accessClient/Server applications

5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam3MICROKERNEL ARCHITECTURE Most OS featured large monolithic kernelOS functionalities provided by the large kernelsScheduling, file system, memory management and moreA monolithic kernel is implemented as a single process with all elements sharing the same address space.A microkernel architecture assigns only a few functions to the kernel , including address spaces, interprocess communications (IPC) and basic scheduling.

5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam4MICROKERNEL ARCHITECTURE Other services are provided by processes called serversServers run in user modeThis approach decouples kernel and server development.AdvantagesSimplifies implementationProvides flexibilitySuitable to the distributed environment5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam5MULTITHREADINGMultithreading is a technique in which a process executing an application is divided into threads that can run concurrently Threads A dispatchable unit of work.It includes a processor context and its own data area for stack.A thread executes sequentially and is interruptable.ProcessA collection of one or more threads and associated system resources.Program in executionBy breaking a single application to multiple threads, it will give modularity of application and timing of application-related events.

5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam6MULTITHREADINGIt is useful for applications that perform a number of essentially independent tasks that do not need to be serialized.Example is a database server that listens for and processes numerous client requestsLess overhead for switching threadsThreads are useful for structuring processes that are part OS Kernel.

5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam7SYMMETRIC MULTIPROCESSINGCharacteristicsThere are multiple processorsThese processors share the main memory and I/O facilities, interconnected by a communication bus or other internal connection scheme.All processors can perform the same functions.The OS of an SMP schedules processes or threads across all of the processors.5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam8ADVANTAGES OF SMP OVER UNIPROCESSOR ARCHITECTUREPerformance : Multiprogramming and multiprocessing

5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam9

Figure 1: Multiprogramming and MultiprocessingADVANTAGES OF SMP OVER UNIPROCESSOR ARCHITECTUREAvailability Failure of single processor does not halt the machineIncremental growth Enhance Performance by adding a processorScaling Vendors can offer a range of products with different prices and different performance characteristics.

5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam10SYMMETRIC MULTIPROCESSINGSMP is useful for non-threaded processes, because several process can run in parallel.Existence of multiple processors is transparent to the user.OS take care of scheduling of threads or processes on individual processors and of synchronization among processors. 5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam1111DISTRIBUTED OPERATING SYSTEMSIt provides the illusion of a single main memory space and a secondary memory space plus other unified access facilities such as DFS.AdvanatgesResponsivenessAvailabilityResource sharing Incremental growthEnd user productivity.5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam12OBJECT ORIENTED DESIGNMost recent innovationIt lends discipline to the process of adding modular extensions to a small kernel At OS level, an object-based structure enables programmers to customize the OS without disrupting system integrityObject orientation also eases the development of distributed tools and full-blown distributed OS.5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam13CONCLUSIONOver the years , there has been a gradual evolution of OS structure and capabilities.In recent years a number of design elements have introduced in both new OS and new release of existing OS that create a major change in the nature of Operating Systems5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam14REFERENCESOperating System : Internals and Design : Seventh Edition by William Stallings 5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam15THANK YOU5-Aug-14Dept of CSE, Mar Athanasius College of Engineering, Kothamangalam16