Voltage Scaling Algorithms

Dynamic Voltage Scaling (DVS) has been a key technique in reducing energy dissipation by lowering the supply voltage and operating frequency. The DVS algorithms are shown to be able to make dramatic energy savings. However, to provide real-time guarantees, DVS must consider deadlines and periodicity of real-time tasks, requiring integration with the real-time scheduler. In this project, I have attempted to mimic some of the important scheduling algorithms, such as Rate Monotic Scheduling (RM) and Earliest Deadline First scheduling (EDF), and the effect of voltage scaling algorithms on them.

There are 4 such algorithms simulated:

• NO SCALING (No voltage scaling)
• STATIC (Frequency scaled at the start and remains unchanged throughout)
• PAST (Frequency is scaled dynamically depending on the previous interval)
• AGED_AVERAGES (Frequency is scaled dynamically depending on the running average of the utilization

The purpose of this project is to demonstrate the advantages of using voltage scaling algorithms. All four voltage scaling algorithms have been simulated using both RM and EDF scheduling mechanisms.

There are two basic assumptions made in the simulations:

• Tasks are not pre-emptible.
  Pre-emption means the ability of the operating system to preempt or stop a currently scheduled task in favour of a higher priority task
• For every task, Deadline = Period.
  This means that every iteration of a task must be completed by the next successive iteration for it to not miss its deadline. The task arrives at time intervals that equal its period.

Click on one of the links below to view the tool:

1. NO SCALING
2. STATIC algorithm
3. PAST algorithm
4. AGED_AVERAGES algorithm

If you need help using the tool, click here for a Help Me file

Voltage Scaling Algorithms
Computer Architecture, Fall 2005