1. RELATED BACKGROUND WORK OZLEM BILGIR

2. OUTLINE 1- Gandhi et al., Optimal Power Allocation in Server Farms, SIGMETRICS’09 2-Chen et al., Managing Server Energy and Operational Costs in Hosting Centers, SIGMETRICS’05 3- Raghavendra et al., No “Power” Struggles: Coordinated Multi-level Power Management for the Data Center, ASPLOS’08

3. Gandhi et al., SIGMETRICS’09 What is the best power allocation model for better response time? Less servers with higher frequency? More servers with lower frequency?

4. Gandhi et al., SIGMETRICS’09 (cont.) Optimal power allocation depends on “power-frequency relationship” Power-frequency relationship depends on many factors.

5. Gandhi et al., SIGMETRICS’09 (cont.) Power- frequency relation depends on: Voltage/frequency scaling technique

6. Gandhi et al., SIGMETRICS’09 (cont.) Experimental Results: Open Server Farm;

7. Gandhi et al., SIGMETRICS’09 (cont.) Experimental Results: Close Server Farm;

8. Gandhi et al., SIGMETRICS’09 (cont.) Summary: -Many factors( frequency scaling technique, arrival rate, total power budget, open/close server configuration.. etc.) affect mean response time

9. Chen et al., SIGMETRICS’05 Data Centers should be able to meet SLA Over-provisioning service capacity to meet SLA for worst case is one option Urgaonkar et. Al, Ranjan et. Al. Chandra et.al looked at finding right capacity and distributing right capacity across different applications to meet SLA Still wasting servers, hence money!!!

10. Chen et al., SIGMETRICS’05(cont.) m1 m2 m3

11. Chen et al., SIGMETRICS’05(cont.) Problem Formulation & Methodology: Total Cost: Server allocation & f modulation period

12. Chen et al., SIGMETRICS’05(cont.) 3 different approaches; – Queuing Theory Based Approach – Control Theoretic Approach – Hybrid Approach

13. Chen et al., SIGMETRICS’05(cont.) 3 different approaches; – Queuing Theory Based Approach – Control Theoretic Approach – Hybrid Approach

14. Chen et al., SIGMETRICS’05(cont.) Queuing Theory Based Approach: where

15. Chen et al., SIGMETRICS’05(cont.) Control Theoretic Approach:

16. Chen et al., SIGMETRICS’05(cont.) Feedback Control of Aggregate Frequency Rf & Rwi are the weights

17. Chen et al., SIGMETRICS’05(cont.) Server Allocation: # of servers for min. Energy:

18. Chen et al., SIGMETRICS’05(cont.) Server allocation Decision Mechanism: 1. m(u-1) > min(m*(u), m(u)) m(u) = min(m*(u), m(u)) 2. otherwise; Cost of turning on one server: Bo Red. in power cost:

19. Chen et al., SIGMETRICS’05(cont.) Summary: -Control theoretical method is similar, but not the same with my works -Turning on-off/DVFS decision mechanism can be improved

20. Raghavendra et al., ASPLOS’08 There are many separate power management solutions addressing different problems Their collection may be non-optimal or unstable There is a need for coordinated solution which is a combination of separate solutions

21. Raghavendra et al., ASPLOS’08(cont.)

23. Summary: -Combining different techniques will give better, more stable, and consistent results