CS162 Operating Systems and Systems Programming Lecture 2 History of the World Parts 1 5 Operating Systems Structures August 31st 2008 Prof John Kubiatowicz http inst eecs berkeley edu cs162 Review Virtual Machine Abstraction Application Operating System Virtual Machine Interface Physical Machine Interface Hardware Software Engineering Problem Turn hardware software quirks what programmers want need Optimize for convenience utilization security reliability etc 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 31 09 Kubiatowicz CS162 UCB Fall 2009 Lec 2 2 Review 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 System 8 31 09 Kubiatowicz CS162 UCB Fall 2009 Lec 2 3 Review Address 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 Virtual Physical CPU 8 31 09 Addresses MMU Addresses Kubiatowicz CS162 UCB Fall 2009 Lec 2 4 Review Example of Address Translation Data 2 Code Data Heap Stack Code Data Heap Stack Stack 1 Heap 1 Code 1 Stack 2 Prog 1 Virtual Address Space 1 Prog 2 Virtual Address Space 2 Data 1 Heap 2 Code 2 OS code Translation Map 1 OS data Translation Map 2 OS heap Stacks 8 31 09 Physical Address Space Kubiatowicz CS162 UCB Fall 2009 Lec 2 5 Goals for Today Finish Protection Example History of Operating Systems Really a history of resource driven choices Operating Systems Structures Operating Systems Organizations Abstractions and layering Note Some slides and or pictures in the following are adapted from slides 2005 Silberschatz Galvin and 8 31 09 Kubiatowicz CS162 UCB Fall 2009 Lec 2 6 Gagne Many slides Gagne generated from lecture notes by The other half of protection Dual 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 exceptions 8 31 09 Kubiatowicz CS162 UCB Fall 2009 Lec 2 7 UNIX System Structure User Mode Applications Standard Libs Kernel Mode Hardware 8 31 09 Kubiatowicz CS162 UCB Fall 2009 Lec 2 8 Moore s Law Change Drives OS Change CPU MHz Cycles inst DRAM capacity Disk capacity Net bandwidth addr bits users machi ne Price 1981 10 3 10 128KB 2009 Quad 3 2G 0 25 0 5 6GB Factor 1 280 6 40 49 152 10MB 9600 b s 16 1 5TB 150 000 1 Gb s 110 000 64 4 10s 1 0 1 25 000 3 500 0 2 Typical academic computer 1981 vs 2009 8 31 09 Kubiatowicz CS162 UCB Fall 2009 Lec 2 9 Moore 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 I 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 work 8 31 09 Kubiatowicz CS162 UCB Fall 2009 Lec 2 10 Dawn of time ENIAC 1945 1955 The machine designed by Drs Eckert and Mauchly was a monstrosity When it was finished the ENIAC filled an entire room weighed thirty tons and consumed two hundred kilowatts of power http ei cs vt edu history ENIAC Richey HTML 8 31 09 Kubiatowicz CS162 UCB Fall 2009 Lec 2 11 History Phase 1 1948 1970 Hardware Expensive Humans Cheap When computers cost millions of s optimize for more efficient use of the hardware Lack of interaction between user and computer User at console one user at a time Batch monitor load program run print Optimize to better use hardware When user thinking at console computer idle BAD Feed computer batches and make users wait Autograder for this course is similar No protection what if batch program has bug 8 31 09 Kubiatowicz CS162 UCB Fall 2009 Lec 2 12 Core Memories 1950s 60s The first magnetic core memory from the IBM 405 Alphabetical Accounting Machine Core Memory stored data as magnetization in iron rings Iron cores woven into a 2 dimensional mesh of wires Origin of the term Dump Core Rumor that IBM consulted Life Saver company See http www columbia edu acis history core html 8 31 09 Kubiatowicz CS162 UCB Fall 2009 Lec 2 13 History Phase 1 late 60s early 70s Data channels Interrupts overlap I O and compute DMA Direct Memory Access for I O devices I O can be completed asynchronously Multiprogramming several programs run simultaneously Small jobs not delayed by large jobs More overlap between I O and CPU Need memory protection between programs and or OS Complexity gets out of hand Multics announced in 1963 ran in 1969 1777 people contributed to Multics 30 40 core dev Turing award lecture from Fernando Corbat key researcher On building systems that will fail OS 360 released with 1000 known bugs APARs Anomalous Program Activity Report OS finally becomes an important science How to deal with complexity UNIX based on Multics but vastly simplified 8 31 09 Kubiatowicz CS162 UCB Fall 2009 Lec 2 14 A Multics System Circa 1976 The 6180 at MIT IPC skin doors open circa 1976 We usually ran the machine with doors open so the operators could see the AQ register display which gave you an idea of the machine load and for convenient access to the EXECUTE button which the operator would push to enter BOS if the machine crashed http www multicians org multics stories html 8 31 09 Kubiatowicz CS162 UCB Fall 2009 Lec 2 15 Early Disk History 1973 1 7 Mbit sq in 140 MBytes 8 31 09 1979 7 7 Mbit sq in 2 300 MBytes Contrast Seagate 2TB 400 GB SQ in 3 in disk Kubiatowicz CS162 UCB Fall 2009 4 platters Lec 2 16 Administrivia Waitlist Everyone has been let into the class Cs162 xx accounts
View Full Document
Unlocking...