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

Active
Core Activity
Idle except for scheduler
Active
Idle Decrypt/Render
Time (ms)
0 10 20 30 40 50 60 70
Figure 1.3 Core Activity Patterns – Blu-Ray Playback
Detecting patterns at the CPU-level is also advantageous since it allows component-level
patterns to be discerned from aggregate patterns. Consider Figure 1.4. The top figure
shows total CPU power consumption for a multi-core processor. The core-level power
consumption is shown in the subsequent four figures. Though the individual cores have a
regular, easily detectable pattern, the aggregate power obscures much of the periodic
behavior. This concept extends to the complete system in which individual core or thread
usage patterns induce similar patterns in shared resources such as memory or I/O devices.
Tracking and predicting CPU usage patterns provides the opportunity to more effectively
adapt power and performance to match demand of the complete system.
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