Quiz: Bad Chinese Food Challenge. Three aspects of design. Lessons from the market. From market to silicon. Eighty percent of success is showing up.

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1 Quiz: Bad Chiese Food Challege Eighty percet of success is showig up." Woody Alle You are give 00 marbles. 50 red ad 50 yellow There are two empty idetical baskets. Distribute all the marbles i the two baskets such that if I radomly, without lookig, reach ito oe of the baskets ad pull out oe marble, I have the highest probability of pullig out a yellow marble. Give the approximate probabilities. Basket #: red yellow Name: Basket #2: red yellow Probability of pickig yellow: "What does showbusiess teach you? Three aspects of desig It teaches you that desig is war; it is a power struggle betwee the produces, directors, authors, everyoe who wats to be ivolved.." Ted Nelso (Iteret Pioeer) + ISA orgaizatio hardware - Programmer visible istructio set - High-level desig (chip + chipset) - Detailed desig (VLSI, package) architecture Everyoe wats to direct. Hollywood proverb From market to silico Lessos from the market Marketplace <eeds of users> Existig applicatio software <legacy code ISA> Desig process Fuctioal requiremets of architecture <bkwd compatibility> Implemetatio of architecture family <desig optimizatio> Separate architecture desig ad techology Icreases ability to adapt arch family Backward compatibility ecessary to compete Must support existig apps Marketplace demads performace cheap Users wat speed, but will oly pay so much price Arch desig performace

2 DRAM costs Quatifyig Cost ad Performace All problems i Computer Sciece ca be solved by aother level of idirectio. Butler Lampso Ay performace problem ca be solved by removig a level of idirectio. M. Haertel Itel Petium III Cost Quatifyig Cost Need to uderstad cost of computers ~ IC cost. Number of square dies that ca be placed o a roud wafer π ( 2 wafer diameter)2 π wafer diameter diesper wafer die area 2 die area Percetage of dies per wafer free from maufacturig defects defects per area die area die yield wafer yie ld + α α Number of good dies per wafer gooddies per wafer dies per wafer die yield Example Example MIPS 4600 (b) Fid cost per projected good die (utested, upkged) 77 mm2 die area die cost Wafer cost $30 (a) Fid # good chips for -cm wafer diameter defect per cm2, wafer yield 95%, α3.0 77mm2.77cm2die area π ( 2 ) 2 π dies per wafer die yield gooddies per wafer wafer cost wafer cost $ 30 $ 8.82 good dies per wafer die per wafer die yield 70 (c) Fid IC cost Wafer cost $30 cost per uit time testig time $.083/ sec*0sec $.77 die yield.478 MIPS 4600: PQFP package testig cost Pi cout < 2 (MIPS 4600 has 8 pis) Package cost $2 Test time 0 sec Test cost per hour $300 Assume fial test yield IC cost diecost + testigcost + packagig cost $ $. 77+ $2 $32.59 fial test yiel d 2

3 System cost Cabiet (6%) Sheet metal, plastic, power supply, fa Cables, uts, bolts, shippig box Processor board (37%) Processor (22%) DRAM (5%), Video card (5%), maiboard (5%) I/O devices (37%) Keyboard/mouse (3%) Moitor (9%) HD/DVD/etc (5%) Software (%) Performace Example My car (X) travels a distace of i oe hour Time betwee start ad completio of evet is hour Executio time Your car (Y) travels a distace of i two hours Ituitio: my car is twice as fast as your car Ituitio assumes performace speed executio executio Is ituitio correct? executiotimeof your car (Y) executiotimeof my car (X) Implies X performs times better tha Y performac e speed time of Y time of X speed of Y speed of X executiotime speed of X performace of X speed of Y performace of Y Speed is oe measure of performace, throughput is aother Speed or throughput Respose time: time it takes to complete oe task Throughput: time it takes to complete may tasks Depeds o user s preferece, but Must be cosistet (same workload) Must be i uits of time (observed period) Types of time Wall clock time, respose time, elapsed time, executio time User CPU time System CPU time 0.0u 0.02s 0: % Performace icrease decrease i overall executio time Time waits for o oe Golde Rule of Performace Evaluatio Esure measured results are determiistic (reproducible) Dedicated rus, uloaded system Corollary to the golde rule Whe evaluatig CPU performace, igore system performace (I/O) i this class CPU performace user CPU time System performace elapsed time icludig I/O Bechmarkig Evaluatio of machie performace for a give workload Methods Real programs Modified apps (cit00, cfp00 of SPEC) Kerels Livermore Kerels, LiPACK Toy Bechmarks accuracy Sieve of Eratosthees (highest commo factor), quicksort Sythetic Bechmarks Whetstoe, Dhrystoe Problems Bechmarks drive vedors to improve bechmarks How do we compare a suite of applicatios 3

4 Lies, dar lies, ad statistics To miimize C3 is.5x faster tha Usig C2 for total Prog Bexecutio time Cheatig o results Apples to orages C is 2.4x faster tha C2 Defie methods for comparisos of C workloads is.5x faster tha C3 (bechmarks) C3 is.5x faster tha C2 How to fairly compare multiple machies ad codes Program A Program B Total Computer C2 is 0x faster tha C for Prog A C is 0x faster tha C2 for Prog B C3 is 0x faster tha C2 for Prog A Computer Computer 3 0 All quatifiable methods should be proportioal to total executio time the great comparator esurig reflectio of real performace. Let s get mea Arithmetic mea Arithmetic mea (weighted) i timei What about uequal emphasis of codes i suite? *Both track total executio time i weighti timei Computer Computer 2 Computer 3 Program A 00 0 Program B Total Weighted arithmetic mea example Arithmetic mea (weighted) i Computer A Computer B Computer C weighti timei W.5, W Prog Prog 2 Comp A 000 W.909,W Comp B 0 00 W.999,W Comp C Be ormal Normalized executio time: ormalize to a particular machie by dividig all executio times by chose machie s time Example: Program P has the followig executio times: O machie A: 0 secs O machie B: 00 secs O machie C: 50 secs Normalized to A: A, B0, C5 Normalized to B: A., B, C.5 Executio time ratio Gettig Meaer Takig the average of the ormalized times Normalized example Normalized arithmetic mea i Executiotimeratioi Comp A Prog Prog Normalized geometric mea ratioi Executiotime i Comp B Comp C 0 00 i Executiotimeratioi ratioi Executiotime Normalized to A Normalized to B Normalized to C A B C A B C A B C ETR P ETR P Normalized to A Normalized to B Normalized to C A B C A B C A B C Bad idea NAM NGM i 4

5 Geometric vs. Arithmetic Arithmetic mea Provides weighted average Pros: proportioal to overall executio time Cos: Ca be rigged easily (disproportioate problem size) Caot use with ormalizig Normalized Geometric mea Provides relative performace of machies to ref Pros: same results regardless of ref machie Cos: Not proportioal to overall executio time Large % chage i small overall time cotributor ca skew Suggestios Weight programs accordig to their actual frequecy Use problem size to pre-ormalize program executio time Combie approaches: summary of simple meas ad relative performace to base machie 5