Administrivia Computer Systems Architecture CMSC 411 Unit 1 Computer Design and Evaluation Class web pages are at http www cs umd edu class fall2004 cmsc411 and linked in from CS dept class web pages Class accounts for project will be on CSIC Linux cluster First homework for Unit 1 announced Thursday 9 2 Start reading Ch 1 of H P Alan Sussman August 30 2004 CMSC 411 Alan Sussman What can you expect to learn in this course Introduction Why are you taking this course You really liked the material in 311 and want to learn more The course time fit into your schedule well You needed upper level CS courses and chose this one at random All the courses you really wanted to take were filled CMSC 411 Alan Sussman 3 Syllabus What to look for in buying a PC brag to parents and friends How computer architecture affects programming style How programming style affect computer architecture Variations on interconnection networks A great deal of jargon CMSC 411 Alan Sussman 4 The Textbook H P More on web page Importance of doing the homework Lecture notes available on the web you can print them before coming to class and then add your own notes I will try to put them up in time I ll correct any typos errors after each lecture and re post I ll post homework and exam answers after the due date password protected and you ll get email with the password account name cmsc411 CMSC 411 Alan Sussman 2 Everyone complains about it Virtually everyone uses it You can handle it but you have to work at it do the reading Through lecture notes other references etc I ll try to help you put it all together 5 CMSC 411 A Sussman from D O Leary CMSC 411 Alan Sussman 6 1 Chapter 1 of H P Early development steps Read Chapter 1 you can skip the economics of cost vs price Historical Perspective Section 1 11 Computers as we know them are roughly 60 years old The von Neumann machine model that underlies computer design is only partially von Neumann s Why does Konrad Zuse say he had the bad luck of being too early Optional Read his own recollections in TR 180 of ETH Z rich http www inf ethz ch research publications show php what 180 la ng en type tr contains both German and English No one was able to successfully patent the idea of a stored program computer much to the dismay of Eckert and Mauchly CMSC 411 Alan Sussman 7 hardware improvements e g squeezing more circuits into a smaller area improvements in instruction set design e g making the machine faster on a small number of frequently used instructions improvements in compilation e g optimizing code to reduce memory accesses and make use of faster machine instructions 9 CMSC 411 Alan Sussman 10 Why a computer scientist should care Computer Architecture instruction set architecture to choose an architecture that matches a user s needs to compare and benchmark different computers to decide whether an upgrade is costefficient to write a program that exploits the strengths of a given computer which elementary instructions are basic to programming the machine organization memory systems to store information bus systems to move information logical design of CPU recall from 311 hardware what physical components are used to form the computer CMSC 411 Alan Sussman 8 Most powerful computer in 1988 CRAY Y MP 1993 a desktop workstation IBM Power 2 matched its power at less than 10 of the cost How did this happen Faster More storage Cheaper Networking and parallel computing Better user interfaces Ubiquitous applications Development of standards CMSC 411 Alan Sussman CMSC 411 Alan Sussman Perspective An example Later development steps Make input and output easier than wiring circuit boards and reading lights Make programming more easy by developing higher level programming languages so that users did not need to use binary machine code instructions Develop storage devices 11 CMSC 411 A Sussman from D O Leary CMSC 411 Alan Sussman 12 2 Technology is rapidly changing Costs From Sections 1 3 1 4 The average program hogs twice as much memory each year Example Microsoft Transistor density increases by 50 each year Dynamic random access memory DRAM density increases by 60 each year Disk density increases by 50 each year Lifespan of a computer is about 5 years Cost of DRAM drops by about 40 each year CMSC 411 Alan Sussman CPU 22 Monitor 19 Hard drive only 9 DRAM only 5 for 128MB Software 20 OS basic office suite 13 Manufacture of DRAM and other chips Chips are manufactured on wafers circular disks containing many dies chips The wafer is tested and chopped into dies From Figure 1 9 in H P The cost of components in a 1000 PC in 2001 are Fig 1 8 in H P CMSC 411 Alan Sussman CMSC 411 Alan Sussman 14 Wafers and dies To find the cost of a die Number of dies per wafer is at most the area of the wafer divided by the area of the die The cost of the wafer divided by the number of working dies per wafer is the cost of each die The fraction of working dies is called the die yield which decreases as the area of the die increases Rule of thumb p 20 Cost of die is proportional to the square of the die area 15 Computer Systems Architecture CMSC 411 Unit 1 Computer Design and Evaluation CMSC 411 Alan Sussman 16 Administrivia First homework for Unit 1 posted due Sept 14 Alan Sussman September 2 2004 CMSC 411 Alan Sussman CMSC 411 A Sussman from D O Leary 18 3 Comparing performance of two machines Last time Technology trends Definition Performance is equal to 1 divided by execution time smaller better faster cheaper processor memory disks networks etc Wafer yields Problem How to measure execution time Rule of thumb is that cost of die chip is proportional to the square of the die area CMSC 411 Alan Sussman 19 What is time CMSC 411 Alan Sussman 20 Time cont Unix time command example p 26 Usual measurements of time 90 7u 12 9s 2 39 65 The user used the CPU for 90 7 seconds user CPU time The system used it for 12 9 seconds system CPU time Elapsed time from the user s request to completion of the task was 2 minutes 39 seconds 159 seconds And 90 7 12 9 159 65 system performance measures the elapsed time on unloaded single user system CPU performance measures user CPU time on unloaded system the rest of the time was spent waiting for I O or running other programs CMSC 411 Alan Sussman 21 How to measure CPU performance Benchmark a program used to measure performance 22 Reproducibility Benchmarking is a laboratory experiment and needs to be documented as fully as a well run chemistry experiment real programs what is