Computer Architecture

Transcription

1 Computer Architecture Overview Prof. Tie-Fu Che Dept. of Computer Sciece Natioal Chug Cheg Uiv Sprig 2002 Overview- Computer Architecture Course Focus Uderstadig the desig techiques, machie structures, techology factors, evaluatio methods that will determie the form of programmable processors i 2st Cetury Techology Applicatios Programmig Laguages Computer Architecture: Istructio Set Desig Orgaizatio Hardware Iterface Desig (ISA) Operatig Systems Measuremet & Evaluatio History Overview-2

2 Topic Coverage Tetbook: Heessy ad Patterso, Computer Architecture: A Quatitative Approach, 2d Ed., 996.! Fudametals of Computer Architecture (Ch. )! Istructio Set Architecture (Ch. 2)! Pipeliig (Ch. 3)! Pipeliig ad Istructioal Level Parallelism (Ch. 4)! Memory Hierarchy (Ch. 5)! Iput/Output ad Storage, RAID (Ch. 6)! Networks ad Itercoectio Techology (Ch. 7), Multiprocessors (Ch. 8)! Vector, SIMD, MMX, VLIW, EPIC ad DSPs! Cofigurable processors ad computig! Desig space eploratio ad embedded processors Overview-3 Computer Architecture (Graduate): Admiistrative Iformatio Istructors: Prof. Tie-Fu Che Office: 42 Computer Sciece Dept, Tel: et-33, che@cs.ccu.edu.tw T. A: Class: Wed 0:0-:00, Fri 0:0-2:00 Room 0 Tet: Computer Architecture: A Quatitative Approach, 2d Editio (996) Web page: Newsgroup: arch2002 Overview-4

3 ABC of Computer Architecture: Performace, Cost, Power Overview-28 The Performace Metric "X is times faster tha Y" meas ETime(Y) Performace(X) ETime(X) Performace(Y) Speed of Cocorde vs. Boeig 747 Throughput of Boeig 747 vs. Cocorde Overview-30

4 Metrics of Performace Applicatio Programmig Laguage Compiler ISA Aswers per moth Operatios per secod (millios) of Istructios per secod: MIPS (millios) of (FP) operatios per secod: MFLOP/s Datapath Cotrol Fuctio Uits Trasistors Wires Pis Megabytes per secod Cycles per secod (clock rate) Overview-3 Performace! Performace Measures Elapsed time CPU time %time 90.7u 2.9s 2:39 65% Cycle time Law of Performace CPI MIPS MFLOPS SPECmarks! Bechmarks! Averagig Overview-32

5 Aspects of CPU Performace CPU time Secods Istructios Cycles Secods Program Program Istructio Cycle Program Ist Cout CPI Clock Rate X Compiler X (X) Ist. Set. X X Orgaizatio X X Techology X Overview-33 Cycles Per Istructio Average Cycles per Istructio CPI Cycles / Istructio Cout (CPU Time * Clock Rate) / Istructio Cout CPU time CycleTime * Σ CPI i Istructio Frequecy i * I i CPI Σ CPI i * F i where F i I i i Istructio Cout Ivest Resources where time is Spet! Overview-34

6 MIPS - Millio istructios per secod! Problems: MIPS Deped o istructio set Deped o differet programs Ca vary iversely with performace! Marketig metrics istr program program time 0 ist cout clock rate 6 6 eec time 0 CPI 0! Meaigless Idicator of Performace?? 6 Overview-36 MFLOPS - Millio floatig-poit operatios per secod M FLOPS FP ops program program tim e 0 6! Problems: " Must be floatig-poit itesive " Some programs perform o FP " ot oly chages o miture of Iteger & FP operatios, but o miture of fast ad slow FP! just aother Meaigless Idicator of Performace??! Peak MFLOPS: the performace the maufacture guaratees you wo't eceed Overview-37

7 SPEC: System Performace Evaluatio Cooperative! First Roud programs yieldig a sigle umber ( SPECmarks )! Secod Roud 992 SPECIt92 (6 iteger programs) ad SPECfp92 (4 floatig poit programs)» Compiler Flags ulimited. March 93 of DEC 4000 Model 60: spice: ui.c:/def(sysv,has_bcopy, bcopy(a,b,c) memcpy(b,a,c) wave5: /ali(all,dcomat)/aga/ur4/ur200 asa7: /orecu/aga/ur4/ur2200/lcblas! Third Roud 995 ew set of programs: SPECit95 (8 iteger programs) ad SPECfp95 (0 floatig poit) bechmarks useful for 3 years Sigle flag settig for all programs: SPECit_base95, SPECfp_base95 Overview-39 Summarizig Results: Average! Arithmetic Mea meas for times, CPI tim e i tim e i! Harmoic mea rate meas for rates, MIPS, MFLOPS! Geometric mea ormalize umbers i rate i Overview-40

8 Speedup! Speedup Speedup! Amdahl's Law Improvemet to be gaied from usig faster mode is limited by the fractio of the time the faster mode ca be used Cosider a ehacemet speedups fractio f of a task by S! Eamples Speedup o ld tim e ew tim e ew old r ate rate ( f ) + ( f / S ) f 90%, S 5 Speedup (. 9 0 ) + (. 9 0 / 5) 3. 6 Overview-43 Amdahl's Law Speedup due to ehacemet E: ETime w/o E Performace w/ E Speedup(E) ETime w/ E Performace w/o E Suppose that ehacemet E accelerates a fractio F of the task by a factor S, ad the remaider of the task is uaffected Overview-44

9 Amdahl s Law ETime ew ETime old ( - Fractio ehaced ) + Fractio ehaced Speedup ehaced Speedup ETime old ETime ew ( - Fractio ehaced ) + Fractio ehaced Speedup ehaced Overview-45 Amdahl s Law! Floatig poit istructios improved to ru 2X; but oly 0% of actual istructios are FP ETime ew ETime old (0.9 +./2) 0.95 ETime old Speedup Law of dimiishig retur: Focus o the commo case! Overview-46

10 Amdahl's Law Corollary! Icreasig speedup f 50%, S.0 Speedup S 0 Speedup S Speedup.0 (.5) + (.5/.).88 (.5) + (.5/0) (.5) + (.5/ ) 20.! Boud Speedup < f! Eamples f % 5% 0% 20% 50% /( -f ) Overview-47 Cost/Performace What is Relatioship of Cost to Price?! Recurrig Costs Compoet Costs Direct Costs (add 25% to 40%) recurrig costs: labor, purchasig, scrap, warraty! No-Recurrig Costs or Gross Margi (add 82% to 86%) (R&D, equipmet maiteace, retal, marketig, sales, fiacig cost, preta profits, taes! Average Discout to get List Price (add 33% to 66%): volume discouts ad/or retailer markup List Price Avg. Sellig Price Average Discout Gross Margi Direct Cost Compoet Cost 25% to 40% 34% to 39% 6% to 8% 5% to 33% Overview-5

11 Eergy/Power! Power dissipatio: rate at which eergy is take from the supply (power source) ad trasformed ito heat PE/t! Eergy dissipatio for a give istructio depeds upo type of istructio (ad state of the processor) P(/CPUTime)* Σ E i i * I i Overview-55 Summary, #2! Amdahl s Law: Speedup ETime old ETime! CPI Law: ew ( - Fractio ehaced ) + Fractio ehaced Speedup ehaced CPU time Secods Istructios Cycles Secods Program Program Istructio Cycle! Eecutio time is the REAL measure of computer performace!! Good products created whe have: Good bechmarks, good ways to summarize performace! Differet set of metrics apply to embedded systems Overview-57