CS162 Operating Systems and Systems Programming Lecture 2 History of the World Parts 1—5 Operating Systems StructuresGoals for TodayWhat if we didn’t have an Operating System?Simple OS: What if only one application?MS-DOS Layer StructureMore thoughts on Simple OSMore complex OS: Multiple AppsExample: Protecting Processes from Each OtherAddress TranslationExample of Address TranslationDual Mode OperationUNIX System StructureMoore’s Law Change Drives OS ChangeMoore’s law effectsAdministriviaAdministriva: Time for Project SignupAcademic Dishonesty PolicyBabbage’s Mechanical Computer (1822-)Dawn of time ENIAC: (1945—1955)History Phase 1 (1948—1970) Hardware Expensive, Humans CheapPunch Cards (1940s & 60s)Core Memories (1950s & 60s)History Phase 1½ (late 60s/early 70s)A Multics System (Circa 1976)Early Disk HistoryHistory Phase 2 (1970 – 1985) Hardware Cheaper, Humans ExpensiveThe ARPANet (1968-1970’s)Slide 28ARPANet Evolves into InternetTypes of NetworksNetwork Components (Examples)History Phase 3 (1981— ) Hardware Very Cheap, Humans Very ExpensiveHistory Phase 3 (con’t) Graphical User InterfacesHistory Phase 4 (1988—): Distributed SystemsHistory Phase 4 (1988—): InternetNetwork “Cloud”Regional Nets + BackboneBackbones + NAPs + ISPsComputers Inside the CoreThe Morris Internet Worm (1988)LoveLetter Virus (May 2000)History Phase 5 (1995—): Mobile SystemsDatacenter is the ComputerMigration of Operating-System Concepts and FeaturesHistory of OS: SummaryImplementation Issues (How is the OS implemented?)ConclusionCS162Operating Systems andSystems ProgrammingLecture 2History of the World Parts 1—5 Operating Systems StructuresJanuary 21, 2010Ion Stoicahttp://inst.eecs.berkeley.edu/~cs162Lec 2.21/21/10 Ion Stoica CS162 ©UCB Spring 2010Goals for Today•Operating Systems Structure•History of Operating Systems–Really a history of resource-driven choices•Operating Systems Organizations•Abstractions and layeringNote: Some slides and/or pictures in the following areadapted from slides ©2005 Silberschatz, Galvin, and Gagne. Many slides generated from lecture notes by Joseph.Lec 2.31/21/10 Ion Stoica CS162 ©UCB Spring 2010What if we didn’t have an Operating System?•Source CodeCompilerObject CodeHardware•How do you get object code onto the hardware?•How do you print out the answer?•Once upon a time, had to Toggle in program in binary and read out answer from LED’s!Altair 8080Lec 2.41/21/10 Ion Stoica CS162 ©UCB Spring 2010Simple OS: What if only one application?•Examples:–Very early computers–Early PCs–Embedded controllers (elevators, cars, etc)•OS becomes just a library of standard services–Standard device drivers–Interrupt handlers–Math librariesLec 2.51/21/10 Ion Stoica CS162 ©UCB Spring 2010MS-DOS Layer StructureLec 2.61/21/10 Ion Stoica CS162 ©UCB Spring 2010More thoughts on Simple OS•What about Cell-phones, Xboxes, etc?–Is this organization enough?•Can OS be encoded in ROM/Flash ROM? •Does OS have to be software?–Can it be Hardware?–Custom Chip with predefined behavior–Are these even OSs?Lec 2.71/21/10 Ion Stoica CS162 ©UCB Spring 2010More complex OS: Multiple Apps•Full Coordination and Protection–Manage interactions between different users–Multiple programs running simultaneously–Multiplex and protect Hardware Resources»CPU, Memory, I/O devices like disks, printers, etc•Facilitator–Still provides Standard libraries, facilities•Would this complexity make sense if there were only one application that you cared about?Lec 2.81/21/10 Ion Stoica CS162 ©UCB Spring 2010Example: Protecting Processes from Each Other•Problem: Run multiple applications in such a way that they are protected from one another•Goal: –Keep User Programs from Crashing OS–Keep User Programs from Crashing each other–[Keep Parts of OS from crashing other parts?]•(Some of the required) Mechanisms:–Address Translation–Dual Mode Operation•Simple Policy:–Programs are not allowed to read/write memory of other Programs or of Operating SystemLec 2.91/21/10 Ion Stoica CS162 ©UCB Spring 2010CPUMMUVirtualAddressesPhysicalAddressesAddress Translation•Address Space–A group of memory addresses usable by something –Each program (process) and kernel has potentially different address spaces.•Address Translation:–Translate from Virtual Addresses (emitted by CPU) into Physical Addresses (of memory)–Mapping often performed in Hardware by Memory Management Unit (MMU)Lec 2.101/21/10 Ion Stoica CS162 ©UCB Spring 2010Example of Address TranslationProg 1VirtualAddressSpace 1Prog 2VirtualAddressSpace 2CodeDataHeapStackCodeDataHeapStackData 2Stack 1Heap 1OS heap & StacksCode 1Stack 2Data 1Heap 2Code 2OS codeOS dataTranslation Map 1 Translation Map 2Physical Address SpaceLec 2.111/21/10 Ion Stoica CS162 ©UCB Spring 2010Dual Mode Operation•Hardware provides at least two modes:–“Kernel” mode (or “supervisor” or “protected”)–“User” mode: Normal programs executed •Some instructions/ops prohibited in user mode:–Example: cannot modify page tables in user mode»Attempt to modify Exception generated •Transitions from user mode to kernel mode:–System Calls, Interrupts, Other exceptionsLec 2.121/21/10 Ion Stoica CS162 ©UCB Spring 2010UNIX System StructureUser ModeKernel ModeHardwareApplicationsStandard LibsLec 2.131/21/10 Ion Stoica CS162 ©UCB Spring 2010Moore’s Law Change Drives OS ChangeTypical academic computer 1981 vs 20090.2$3,500$25,000 0.1 110s46416110,0001 Gb/s9600 b/s150,0001.5TB10MB49,1526GB128KB1,2806—40 Quad 3.2G0.25—0.5103—10 Factor20091981Price#users/machine# addr bitsNet bandwidthDisk capacityDRAM capacityCPU MHz,Cycles/instLec 2.141/21/10 Ion Stoica CS162 ©UCB Spring 2010Moore’s law effects•Nothing like this in any other area of business•Transportation in over 200 years: –2 orders of magnitude from horseback @10mph to Concorde @1000mph–Computers do this every decade (at least until 2002)!•What does this mean for us?–Techniques have to vary over time to adapt to changing tradeoffs•Place a lot more emphasis on principles–The key concepts underlying computer systems–Less emphasis on facts that are likely to change over the next few years…•Let’s examine the way changes in $/MIP has radically changed how OS’s workLec 2.151/21/10 Ion Stoica CS162 ©UCB Spring 2010Administrivia•Waitlist: Everyone has been let into the
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