COS 318: Operating SystemsLecture 2: Continuation of Introduction Overview of Operating SystemsJaswinder Pal SinghComputer Science DepartmentPrinceton University(http://www.cs.princeton.edu/courses/cos318/)2Logistics!Precepts:"Wed: 8:30-9:30pm, 105 CS building !Please check times for Design review and Assignment 1 due date on the Web site!Reminder:"Register for the cos318 mailing list today!3Today!Overview of OS structure!Overview of OS components4Previous Lecture!Course Staff and Logistics!What is an operating system?!Evolution of computing and operating systems!Why study operating systems?!What’s in COS 318?5Today!Evolution of computing and operating systems!Why study operating systems?!What’s in COS 318?!Overview of Operating Systems6A Typical Academic Computer (1986 v. 2007)19862007RatioCPU clock4Mhz4!3Ghz3000x$/machine$60k$6001/100xDRAM1MB2GB2000xDisk50MB0.5-1TB10K-20KxNetwork BW10Mbits/sec1GBits/sec100xAddress bits32642xUsers/machine10s< 1>10x$/Performance$60k$600/30001/200,000x7!Performance/Price doubles every 18 months!100x per decade!Progress in next 18 months = ALL previous progress"New storage = sum of all old storage (ever)"New processing = sum of all old processing.!This has led to some broad phases in computing, and correspondingly in the nature of operating systems15 years ago!Courtesy Jim GrayExponential Growth in Computing, Comm.Generations:• (1945–55) Vacuum Tubes• (1955–65) Transistors and Batch Systems• (1965–1980) ICs and Multiprogramming• (1980–Present) Personal ComputersHistory of Computers and OSes!Hardware very expensive, humans cheap!When was the first functioning digital computer built?!What was it built from?!How was the machine programmed?!What was the operating system?!The big innovation: punch cards!The really big one: the transistor"Made computers reliable enough to be sold to and operated by customers9Phase 1: The Early Days!Hardware still expensive, humans relatively cheap!An early batch system!Programmers bring cards to reader system!Reader system puts jobs on tapePhase 2: Transistors and Batch Systems!An early batch system!Operator carries input tape to main computer!Main computer computes and puts output on tape!Operator carries output tape to printer system, which prints outputPhase 2: Transistors and Batch SystemsPunch cards and Computer Jobs!Integrated circuits allowed families of computers to be built that were compatible!Single OS to run on all (IBM OS/360): big and bloated!Key innovation: multiprogramming!What happens when a job is waiting on I/O!What if jobs spend a lot of the time waiting on I/O?Phase 3: ICs and Multiprogramming!Multiple jobs resident in computer’s memory!Hardware switches between them (interrupts)!Hardware protects from one another (mem protection)!Computer reads jobs from cards as jobs finish (spooling)!Still batch systems: can’t debug online!Solution: time-sharingPhase 3: ICs and Multiprogramming!Time-sharing:!Users at terminals simultaneously!Computer switches among active ‘jobs’/sessions!Shorter, interactive commands serviced fasterhardwareHardwareApp1Time-sharing OSApp2 App2. . .Phase 3: ICs and MultiprogrammingPhase 3: ICs and Multiprogramming!The extreme: computer as a utility: MULTICS (late 60s)!Problem: thrashing as no. of users increases!Didn’t work then, but idea may be back!Let others administer and manage; I’ll just use!ICs led to mini-computers: cheap, small, powerful!Stripped down version of MULTICS, led to UNIX!Two branches (Sys V, BSD), standardized as POSIX!Free follow-ups: Minix (education), Linux (production)17Phase 4: HW Cheaper, Human More Costly!Personal computer"Altos OS, Ethernet, Bitmap display, laser printer"Pop-menu window interface, email, publishing SW, spreadsheet, FTP, Telnet"Eventually >100M units per year!PC operating system"Memory protection"Multiprogramming"Networking18Now: > 1 Machines per User!Pervasive computers"Wearable computers"Communication devices"Entertainment equipment"Computerized vehicle!OS are specialized"Embedded OS"Specially configured general-purpose OS19Now: Multiple Processors per Machine!Multiprocessors"SMP: Symmetric MultiProcessor"ccNUMA: Cache-Coherent Non-Uniform Memory Access "General-purpose, single-image OS with multiproccesor support!Multicomputers"Supercomputer with many CPUs and high-speed communication"Specialized OS with special message-passing support!Clusters"A network of PCs"Commodity OS20Now: Multiple “Cores” per Processor!Multicore or Manycore transition"Intel and AMD have released 4-core and soon 6-core CPUs "SUN’s Niagara processor has 8-cores"Azul Vega8 now packs 24 cores onto the same chip"Intel has a TFlop-chip with 80 cores"Ambric Am2045: 336-core Array (embedded, and accelerators)!Accelerated need for software support"OS support for many cores; parallel programming of applicationsSummary: Evolution of Computers60’s-70’s - Mainframes!Rise of IBM70’s - 80’s – Minicomputers!Rise of Digital Equipment Corporation80’s - 90’s – PCs!Rise of Intel, MicrosoftNow – Post-PC!Distributed applications21Summary: Evolution and Implications for OS22MainframeMiniMicroSystem $ /Worker $10:1 – 100:110:1 – 1:11:10-1:100GoalSystem utilizationOverall costProductivityTargetCapacityFeaturesEase of Use23Today!Evolution of computing and operating systems!Why study operating systems?!What’s in COS 318?!Overview of Operating Systems24Why Study OS?!OS is a key part of a computer system"It makes our life better (or worse) "It is “magic” to realize what we want"It gives us “power”!Learn about concurrency"Parallel programs run on OS"OS runs on parallel hardware: all hw becoming parallel"OS is great way to learn concurrent programming!Understand how a system works"How many procedures does a key stroke invoke?"What happens when program references 0 as a pointer?"Real OS is huge and impossible to read everything, but building a small OS will go a long wayWhy Study OS?!Important for studying further areas"Networking, distributed systems, …!Full employment"New hardware capabilities and organizations"New features"New approaches"E.g. handheld computers, Java, WWW"Engineering tradeoffs, keep changing as the hardware changes from below and the needs of apps from above!Lots of jargon: sound smart (or super-nerdy)2526Today!Evolution of computing and operating systems!Why study operating systems?!What’s in COS 318?!Overview of Operating Systems27What Is in COS 318?!Methodology"Lectures with