Lecture 3 - Quantitative Analysis (2010-01-19)

Lecture 3 - Quantitative Analysis (2010-01-19) - 1 Chapter...

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Unformatted text preview: 1 Chapter 1: Quantitative Analysis Chapter 1: Quantitative Analysis Modern Processor Design: Fundamentals of Superscalar Modern Processor Design: Fundamentals of Superscalar Processors Processors Mark Heinrich School of Computer Science University of Central Florida Define and quantify power ( 1 / 2) Define and quantify power ( 1 / 2) For CMOS chips, traditional dominant energy consumption has been in switching transistors, called dynamic power 2 witched FrequencyS Voltage Load Capacitive Power dynamic = 2 2 / 1 For mobile devices, energy better metric Voltage Load Capacitive Energy dynamic 2 = For a fixed task, slowing clock rate (frequency switched) reduces power, but not energy Capacitive load is a function of number of transistors 3 connected to output and technology, which determines capacitance of wires and transistors Dropping voltage helps both, so went from 5V to 1V To save energy & dynamic power, most CPUs now turn off clock of inactive modules (e.g. Fl. Pt. Unit) 2 Example of quantifying power Example of quantifying power Suppose 15% reduction in voltage results in a 15% reduction in frequency. What is impact on dynamic power? dynamic dynamic dynamic OldPower OldPower witched FrequencyS Voltage Load Capacitive witched FrequencyS Voltage Load Capacitive Power = = = 6 . ) 85 (. ) 85 (. 85 . 2 / 1 2 / 1 3 2 2 4 Define and quantify power (2 / 2) Define and quantify power (2 / 2) Because leakage current flows even when a transistor is off, now static power important too Voltag Curren Powe Leakage current increases in processors with smaller transistor sizes Increasing the number of transistors increases power even if they are turned off In 2006 goal for leakage is 25% of total power Voltage Current Power static static = 5 In 2006, goal for leakage is 25% of total power consumption; high performance designs at 40% Very low power systems even gate voltage to inactive modules to control loss due to leakage 3 Define and quantify dependability (1/3) Define and quantify dependability (1/3) How decide when a system is operating properly? Infrastructure providers now offer Service Level Agreements (SLA) to guarantee that their networking or power service would be dependable Systems alternate between 2 states of service with respect to an SLA: 1. Service accomplishment , where the service is delivered as specified in SLA 2. Service interruption , where the delivered service is 6 different from the SLA Failure = transition from state 1 to state 2 Restoration = transition from state 2 to state 1 Define and quantify dependability (2/3) Define and quantify dependability (2/3) Module reliability = measure of continuous service accomplishment (or time to failure)....
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This note was uploaded on 08/22/2010 for the course CDA 5106 taught by Professor Staff during the Spring '08 term at University of Central Florida.

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Lecture 3 - Quantitative Analysis (2010-01-19) - 1 Chapter...

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