RTS

This project was developed during my Master and PhD studies. It is a framework for dynamic reconfiguration, value-based processor resource allocation in multi-modal or not real-time applications, under schedulability, energy consumption and temperature constraints. The framework is suitable for critical and soft real-time adaptive embedded systems which need guarantees of energy savings. The dynamic allocation is formulated as a discrete and continuous (convex and piecewise linear) optimization problem, for which efficient algorithms were tested. Although the discrete problem is NP-Hard, the others have efficient solution and numerical analysis and simulations have shown that the used algorithms and models achieves very good results, with low computational cost.

Mar 19, 2021

Overview A common way to save energy with computers is exploring the CPU frequency switch capability. The Raspberry Pi uses an ARM1176JZF-S processor and according to the ARM on-line documentation this CPU can be run in any frequency under the maximal one, supported by the processor. To be able to performance any frequency the ARM11 architecture emulate a continuous DVS(Dynamic Voltage Scaling), in a discrete processor. It is accomplished by holding the voltage at the maximum level and then switch the system clock between the maximum frequency and off. In order to apply this the Intelligent Energy Management (IEM) — it is a technology that runs on ARM processor to classify the types of activity and to analyze their processor utilization patterns for global prediction about the future performance required by the system defines frames that are directly related to the performance level. In Figure 1 the system performance requested in the first frame is 50%, so the CPU work at maximum frequency for half of the frame, and then it is turned off for the rest of the frame. In the second frame a performance of 25% of the CPU, and then 75% in the last frame.

Mar 18, 2021

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