02_performance

02_performance - This Unit Metrics Latency and throughput CIS 501 Computer Architecture Reporting performance Benchmarking and averaging CPU

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CIS 501 (Martin/Roth): Performance 1 CIS 501 Computer Architecture Unit 2: Performance Slides originally developed by Amir Roth with contributions by Milo Martin at University of Pennsylvania with sources that included University of Wisconsin slides by Mark Hill, Guri Sohi, Jim Smith, and David Wood. CIS 501 (Martin/Roth): Performance 2 This Unit • Metrics • Latency and throughput • Reporting performance • Benchmarking and averaging • CPU performance equation CIS 501 (Martin/Roth): Performance 3 Readings • Chapter 1.2-1.4 of MA:FSPTCM CIS 501 (Martin/Roth): Performance 4 Performance: Latency vs. Throughput Latency (execution time) : time to finish a fixed task Throughput (bandwidth) : number of tasks in fixed time • Different: exploit parallelism for throughput, not latency (e.g., bread) • Often contradictory (latency vs. throughput) • Will see many examples of this • Choose definition of performance that matches your goals • Scientific program: latency; web server: throughput? • Example: move people 10 miles • Car: capacity = 5, speed = 60 miles/hour • Bus: capacity = 60, speed = 20 miles/hour • Latency: car = 10 min , bus = 30 min • Throughput: car = 15 PPH (count return trip), bus = 60 PPH
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CIS 501 (Martin/Roth): Performance 5 Processor Performance and Workloads • Q: what does latency(ChipA) or throughput(ChipA) mean? • A: nothing, there must be some associated workload Workload : set of tasks someone (you) cares about Benchmarks : standard workloads • Used to compare performance across machines • Either are or highly representative of actual programs people run Micro-benchmarks : non-standard non-workloads • Tiny programs used to isolate certain aspects of performance • Not representative of complex behaviors of real applications • Examples: towers-of-hanoi, 8-queens, etc. CIS 501 (Martin/Roth): Performance 6 Comparing Performance • A is X times faster than B if • Latency(A) = Latency(B) / X • Throughput(A) = Throughput(B) * X • A is X% faster than B if • Latency(A) = Latency(B) / (1+X/100) • Throughput(A) = Throughput(B) * (1+X/100) • Car/bus example • Latency? Car is 3 times (and 200%) faster than bus • Throughput? Bus is 4 times (and 300%) faster than car CIS 501 (Martin/Roth): Performance 7 SPEC Benchmarks • SPEC (Standard Performance Evaluation Corporation) http://www.spec.org/ • Consortium that collects, standardizes, and distributes benchmarks • Post SPECmark results for different processors • 1 number that represents performance for entire suite • Benchmark suites for CPU, Java, I/O, Web, Mail, etc. • Updated every few years: so companies don’t target benchmarks • SPEC CPU 2006 • 12 “integer”: bzip2, gcc, perl, hmmer (genomics), h264, etc. • 17 “floating point”: wrf (weather), povray, sphynx3 (speech), etc.
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This note was uploaded on 10/19/2011 for the course CS 501 taught by Professor Matin during the Fall '10 term at UPenn.

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02_performance - This Unit Metrics Latency and throughput CIS 501 Computer Architecture Reporting performance Benchmarking and averaging CPU

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