Dynamic Voltage and Frequency Management Based on Variable Update Intervals

Transkript

1 Dynamic Voltage and Frequency Management Based on Variable Update Intervals for Frequency Setting Mehrdad Najibi Mostafa Salehi Ali Afzali Kusha Massoud Pedram S. Mehdi Fakhraie Hossein Pedram Presentation given at ICCAD, Nov. 2006

2 Outline Prior Work Dynamic voltage and frequency management Adaptive frequency scheduling based on an effective deadline Effective deadline prediction Frequency scheduling Underload and overload conditions Experimental results

3 Prior work Commercial processors with DVS capability Burd et al, 2000, Arm8 processor core Nowka et al, 2002, PowerPC processor Flautner and Flynn, 2002, arm9 processor core Kihwan et a, al, , 05, StrongArm Sto and Xscale scae... Nakai et al, embedded microprocessor

4 Dynamic Voltage and Frequency Management DVFM architecture [Nakai et al, JSSC-05]

5 Dynamic Voltage Management

6 Dynamic Frequency Management Frequency scheduling based on fixed interval [Nakai et al, JSSC-05]

7 Adaptive Frequency Scheduling Based on an Effective Deadline Fixed Interval Voltage (m mv) Freq. (MH Hz) If it is long : Slow workload tracking (fixed freq step) Max workload Slope (Upper bound) If it is short : Higher Avg. Freq Higher # of unnecessary updates Adaptive Interval Lower updates Time (ms) Power Network Fluctuations Near optimal frequency & voltage 4 up-1 down avg. freq Steady: 4 up-4 down useless changes

8 Effective Deadline Soft Real Time Application Periodic Workloads Arrival of the next workload Ati Active cycles Idle cycles Input rate (1) (2) Hypothetic FIFO output rate f peak = 4f eff E 1 = 16E 2 FIFONotEmpty

9 Prediction of the Effective Deadline Arrival time of the next workload Reported in terms of system cycles Effective Deadline Update the interval Compute the frequency Adaptive Adjustment 2 consecutive increases Interval_step * 2 2 consecutive idecreases Interval_step / 2 Up Interval Next Interval Current Interval Step Next Interval Current Interval Down Interval Step

10 Frequency Adjustment Frequency Up thl thh update Frequency Down thl thh update thl thh Frequency Steady update

11 Overload and Underload Conditions Interval without overload detection Overload (no idle cycle) Slower freq increase (worsen the situation) Interval Interval with overload detection Underload (no active cycle) Slower freq decrease Interval

12 Results (Periodic Workload) 1600 Fixed Interval 1400 Voltage (mv) Voltag ge (mv) FI 80% AI 80% 600 FI 20% AI 20% 800 Time (ms) Frequency (MHz) FI 80% AI 80% FI 20% AI 20% Adaptive Interval Time (ms) Time (ms) Freq. (MHz) Voltage Frequency Time (ms)

13 Results power (mw) )Workload Power Consumption Fixed Interval Adaptive Interval Frequency V DD Power Frequency V DD Power Power (MHz) (mv) (mw) (MHz) (mv) (mw) Reduction 0% Fixed Interval 0.95 Adaptive Interval % 10% % 5 20% % 0 30% % % % % 50% workload % % % 60% % % 70% % % 80% % 90% % % 100% % % 10% 0%

14 Results (Correlated Workloads) 70.00% Power/Op - Pe erfomance Reduct tion 60.00% 50.00% 40.00% 30.00% 20.00% 10.00% Power/Operation Performance 0.00% 0% 10% 20% 30% % 50% 60% 70% Normmalized AI/FI Metrics Correlation Percentage % 90% Delay Power PDP EDP 0.4 0% 20% 40% 60% 80% 100% Correlation Percent

15 Summary Presented an efficient adaptive method to perform dynamic voltage and frequency management (DVFM) for minimizing the energy consumption of microprocessor chips Uses adaptive update intervals for optimal frequency and voltage scheduling Rapidly tracks the workload changes so as to meet soft real-time deadlines Utilizes the correlation between consecutive values of the workload for future workload prediction Because the frequency and voltage update rates are dynamically set based on variable update interval lengths, voltage fluctuations on the power network are minimized The technique leads to power savings of up to 60% for highly correlated workloads compared to DVFM systems based on fixed update intervals.