2. Outline Models Design of experiments

3. Current Scheduler Completely Fair Scheduler(CFS) ◦ Since Linux 2.6.23 ◦ /kernel/sched.c ◦ Maintain balance (fairness) in providing processor time to tasks.  Red-Black Tree

4. Our Ideas Base on ready queue length Base on machine learning Energy-based model

5. Assumptions Core voltage cannot be adjusted to any value, but some pre-defined value. ◦ Level We know N, the number of tasks waiting in the ready queue. Each task is only in core for execution during a short period before being swept out and back to ready queue.

6. Base on Queue Length - 1 Assume the time slice is fixed. ◦ Higher core V => more cycles => more instructions executed => tasks can finish earlier. Two methods ◦ For every period of time, if N increases => raise core voltage. ◦ For every period of time, if N doesn’t decreases => raise core voltage.

7. Base on Queue Length - 2 Assume the instruction retired is fixed. ◦ Higher core V => more cycles => shorter time in core. All N tasks should be executed at least once in T. ◦ TmaxV ≦ T ≦ TminV ◦ Adjust core voltage according to N. T V low V high N t = 6+4 = 10

8. Energy-based Assume the V×t, energy of each task being executed once is fixed. ◦ Similar to the previous one. However, V×t is adjusted according to Battery Power Remaining.

9. Design of Experiment First we measure the power consumption and benchmark performance using L4Linux predefined strategy. ◦ V highest and V lowest. Apply our strategies and measure: ◦ Only one benchmark ◦ Multiple benchmarks  Same  Different

10. Paper Study An Energy Conservation DVFS Algorithm for the Android Operating System ◦ 2012 An Energy Conservation DVFS Algorithm for the Android Operating System ◦ 2010 An Energy Conservation DVFS Algorithm for the Android Operating System ◦ 2005

11. Discussion