Who am I Professor John Kubiatowicz Prof Kubi CS162 Operating Systems and Systems Programming Lecture 1 Background in Hardware Design Alewife project at MIT Designed CMMU Modified SPAR C processor Helped to write operating system Background in Operating Systems Worked for Project Athena MIT OS Developer device drivers network file systems Worked on Clustered High Availability systems CLAM Associates What is an Operating System Peer to Peer August 29 2005 Prof John Kubiatowicz http inst eecs berkeley edu cs162 OceanStore project Store your data for 1000 years Tapestry and Bamboo Find you data around globe Quantum Computing Well this is just cool but probably not apropos 8 29 05 Goals for Today Kubiatowicz CS162 UCB Fall 2005 Lec 1 2 Rapid Underlying Technology Change What is an Operating System And what is it not Examples of Operating Systems design Why study Operating Systems Oh and How does this class operate Note Some slides and or pictures in the following are adapted from slides 2005 Silberschatz Galvin and Gagne 8 29 05 Kubiatowicz CS162 UCB Fall 2005 Lec 1 3 Cramming More Components onto Integrated Circuits Gordon Moore Electronics 1965 8 29 05 Kubiatowicz CS162 UCB Fall 2005 Lec 1 4 Computing Devices Everywhere Computer System Organization Computer system operation One or more CPUs device controllers connect through common bus providing access to shared memory Concurrent execution of CPUs and devices competing for memory cycles 8 29 05 Kubiatowicz CS162 UCB Fall 2005 Lec 1 5 8 29 05 Kubiatowicz CS162 UCB Fall 2005 Functionality comes with great complexity Lec 1 6 Sample of Computer Architecture Topics Input Output and Storage Disks WORM Tape Pentium III Chipset Emerging Technologies Interleaving Bus protocols DRAM Caches Busses Memory Hierarchy adapters Coherence Bandwidth Latency L2 Cache Memory Controllers I O Devices 8 29 05 Disks Displays Keyboards VLSI L1 Cache Instruction Set Architecture Kubiatowicz CS162 UCB Fall 2005 Addressing Protection Exception Handling Pipelining Hazard Resolution Superscalar Reordering Prediction Speculation Vector Dynamic Compilation Networks Lec 1 7 8 29 05 Network Communication Other Processors Proc RAID Pipelining and Instruction Level Parallelism Kubiatowicz CS162 UCB Fall 2005 Lec 1 8 Example Some Mars Rover Requirements How do we tame complexity Serious hardware limitations complexity 20Mhz powerPC processor 128MB of RAM cameras scientific instruments batteries solar panels and locomotion equipment Many independent processes work together Can t hit reset button very easily Must reboot itself if necessary Always able to receive commands from Earth Individual Programs must not interfere Suppose the MUT Martian Universal Translator Module buggy Better not crash antenna positioning software Further all software may crash occasionally Automatic restart with diagnostics sent to Earth Periodic checkpoint of results saved Certain functions time critical Need to stop before hitting something Must track orbit of Earth for communication 8 29 05 Kubiatowicz CS162 UCB Fall 2005 Lec 1 9 Every piece of computer hardware different Different CPU Pentium PowerPC ColdFire ARM MIPS Different amounts of memory disk Different types of devices Mice Keyboards Sensors Cameras Fingerprint readers Different networking environment Cable DSL Wireless Firewalls Questions Does the programmer need to write a single program that performs many independent activities Does every program have to be altered for every piece of hardware Does a faulty program crash everything Does every program have access to all hardware 8 29 05 OS Tool Virtual Machine Abstraction Application Operating System Hardware Lec 1 10 Interfaces Provide Important Boundaries software Virtual Machine Interface instruction set Physical Machine Interface hardware Software Engineering Problem Turn hardware software quirks what programmers want need Optimize for convenience utilization security reliability etc Why do interfaces look the way that they do For Any OS area e g file systems virtual memory networking scheduling What s the hardware interface physical reality What s the application interface nicer abstraction 8 29 05 Kubiatowicz CS162 UCB Fall 2005 Kubiatowicz CS162 UCB Fall 2005 Lec 1 11 History Functionality Stupidity Bugs Management CS152 Machine interface CS160 Human interface Should responsibilities be pushed across boundaries RISC architectures Graphical Interfaces 8 29 05 Kubiatowicz CS162 UCB Fall 2005 Lec 1 12 Virtual Machines Four Components of a Computer System Software emulation of an abstract machine Make it look like hardware has features you want Programs from one hardware OS on another one Programming simplicity Each process thinks it has all memory CPU time Each process thinks it owns all devices Different Devices appear to have same interface Device Interfaces more powerful than raw hardware Bitmapped display windowing system Ethernet card reliable ordered networking TCP IP Fault Isolation Processes unable to directly impact other processes Bugs cannot crash whole machine Protection and Portability Java interface safe and stable across many platforms 8 29 05 Kubiatowicz CS162 UCB Fall 2005 Lec 1 13 Definition An operating system implements a virtual machine that is hopefully easier and safer to program and use than the raw hardware 8 29 05 Virtual Machines con t Layers of OSs You will be working with Nachos When OS crashes restricted to one VM Can aid testing programs on other OSs Kubiatowicz CS162 UCB Fall 2005 Lec 1 14 Nachos Virtual OS Environment Useful for OS development 8 29 05 Kubiatowicz CS162 UCB Fall 2005 Simulation environment Hardware interrupts I O Execution of User Programs running on this platform Lec 1 15 8 29 05 Kubiatowicz CS162 UCB Fall 2005 Lec 1 16 What does an Operating System do What is an Operating System Really Silerschatz and Gavin An OS is Similar to a government Begs the question does a government do anything useful by itself Coordinator and Traffic Cop Manages all resources Settles conflicting requests for resources Prevent errors and improper use of the computer Facilitator Provides facilities that everyone needs Standard Libraries Windowing systems Make application programming easier faster less error prone Some features reflect both tasks E g File system is needed by everyone Facilitator But File system must be Protected Traffic Cop 8 29 05 Kubiatowicz CS162 UCB Fall 2005 Lec 1 17 Most Likely What about 8 29 05 Kubiatowicz CS162 UCB Fall 2005
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