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Copyright by William Lloyd Bircher 2010 - The Laboratory for ...

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5.3 Complete-System Desktop Power Model<br />

In this section results <strong>for</strong> the application of the trickle-down modeling approach are<br />

presented <strong>for</strong> a recent desktop plat<strong>for</strong>m. This plat<strong>for</strong>m differs from the previous server in<br />

terms of process technology, system architecture, manufacturer and workload among<br />

others. It is shown that though this plat<strong>for</strong>m is significantly different than the server, the<br />

trickle-down modeling approach still accurately models power. Of particular importance<br />

are two major differences: subsystem level power management and workload<br />

characteristics. Power management increases the complexity and utility of the power<br />

model as power consumption varies greatly with the application of power management.<br />

Compare this to the server system in which power remains near a constant level due to<br />

subsystems not reducing per<strong>for</strong>mance capacity, and there<strong>for</strong>e power consumption, during<br />

periods of low utilization. Increased power variation is also attributable to desktop-<br />

specific workloads. While server workloads tend to always operate at full speed (e.g.<br />

SPEC CPU) desktop workloads such as SYSmark and 3DMark contain large portions of<br />

low utilization. This exposes the impact of power management and the need to model it.<br />

5.3.1 System Description<br />

To validate the effectiveness of the trickle-down approach the process is applied to a<br />

recent desktop plat<strong>for</strong>m. A comparison of the two systems used in this study (server and<br />

desktop) is provided in Table 5.3. <strong>The</strong>se systems differ in their power management<br />

implementations and subsystem components. <strong>The</strong> desktop system is optimized <strong>for</strong> power<br />

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