Low Power Design, Intel Processors

Computer Organization and Design: The Hardware/Software Interface

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Unformatted text preview: Recap: I/O Summary CS152 Computer Architecture and Engineering Lecture 25 Low Power Design, Advanced Intel Processors ° I/O performance limited by weakest link in chain between OS and device ° Queueing theory is important • 100% utilization means very large latency • Remember, for M/M/1 queue (exponential source of requests/service) - queue size goes as u/(1-u) - latency goes as Tser×u/(1-u) • For M/G/1 queue (more general server, exponential sources) - latency goes as m1(z) x u/(1-u) = Tser x {1/2 x (1+C)} x u/(1-u) ° Three Components of Disk Access Time: • Seek Time: advertised to be 8 to 12 ms. May be lower in real life. • Rotational Latency: 4.1 ms at 7200 RPM and 8.3 ms at 3600 RPM • Transfer Time: 2 to 50 MB per second ° I/O device notifying the operating system: • Polling: it can waste a lot of processor time • I/O interrupt: similar to exception except it is asynchronous ° Delegating I/O responsibility from the CPU: DMA, or even IOP May 3, 2004 John Kubiatowicz (http.cs.berkeley.edu/~kubitron) lecture slides: http://www-inst.eecs.berkeley.edu/~cs152/ 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.2 Slides Borrowed from Bob Broderson Low Power Design 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.3 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.4 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.5 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.6 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.7 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.8 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.9 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.10 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.11 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.12 3/4 × 1/4 = 3/16 3/16 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.13 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.14 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.15 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.16 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.17 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.18 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.19 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.20 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.21 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.22 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.23 5/03/04 ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.24 Desired Throughput 000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000 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system not always computing Back to original goal: Processor Usage Model System Optimizations: • Maximize Peak Throughput • Minimize Average Energy/operation 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 5/03/04 Delivered Throughput Typical Usage ©UCB Spring 2004 CS152 / Kubiatowicz Lec25.25 5/03/04 Delivered Throughput 000 000000000000000000000000000000000000000000000000 00000 00 000000000000 00 00 000000000000000000000000 00 000 0 0000 0000 00 00 00 00 00 00 00 00 00 00 00 00 00 0 0 0 0 0 0 0 0 0 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