Linux Power Management

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1 Linux Power Management Uses one of two types of management Advanced Power Management (APM) older BIOS base power management Advanced Configuration and Power Interface (ACPI) newer More operating system centric (tree structure)

2 Android Power Management Controlled via Power Manager interface No APM or ACPI Allows setting of wake locks Forces the device to remain on Configurable in terms of what stays on Can lead to greatly poor battery life if not properly used

3 Android Power Management overview Applipcation A Application B Application C applications PoweManager Android os PowerManager Aplication framework Power PowerMangerService Android server PManService User space libraries Core Libraries Power Linux kernel Linux Drivers Android Power Management /driver/android/power.c Linux Power Management

KERNEL Display driver Camera driver Keypad driver

4 Power Management Problem (Android) Mobile devices run on battery power Batteries have limited capacity LINUX KERNEL Display driver Camera driver Keypad driver Binder driver USB driver WiFi driver Audio driver P. Management

5 Power Management Solution (Android) Built on top of standard Linux Power Management (PM) More aggressive power management policy Components make requests to keep the power on through wake locks Supports different types of wake locks LINUX KERNEL Display driver Camera driver Keypad driver Binder driver USB driver WiFi driver Audio driver P. Management

6 Android Power Manager Application A PowerManager PM Driver

7 Android Power Manager Application A PowerManager PM Driver new wake lock PARTIAL

8 Android Power Manager Application A PowerManager PM Driver new wake lock PARTIAL create wake lock

9 Android Power Manager Application A PowerManager PM Driver new wake lock PARTIAL create wake lock turn off LCD

10 Android Power Manager Application A PowerManager PM Driver new wake lock PARTIAL create wake lock turn off LCD release release

11 Android Power Manager Application A PowerManager PM Driver new wake lock PARTIAL create wake lock turn off LCD release release turn off CPU

12 Wake Locks Types: ACQUIRE_CAUSES_WAKEUP FULL_WAKE_LOCK ON_AFTER_RELEASE PARTIAL_WAKE_LOCK SCREEN_BRIGHT_WAKE_LOCK SCREEN_DIM_WAKE_LOCK

13 Summary Power Management Android Android Power Manager implements wakelocks to control CPU, screen, backlight Power Management Linux Standard Linux Power Management uses suspend and resume operations

14 Questions and Answers

15 References [1] L. Benini and G. d. Micheli. Case study of performance of real-time Linux on the x86 architecture. The Sixth Real-Time Linux Workshop, pages 18 25, [2] F. Yao and S. Shenker. A scheduling model for reduced CPU energy. the proceedings of PART 98,pages 68 77, [3] M. Stemm and Y. H. Katz. Measuring and reducing energy consumption of network interfaces in hand-held devices. 13th ACM Symposium on Operating Systems principles, pages , [4] M. B. Srivastava and R. W. Brodersen. Predictive system shutdown and other architectural techniques for energy efficient programmable computation. EEE Trans. Very Large Scale Integr. Syst., 4:42 55, [5] Y. Shin and K. Choi. Proceedings of the 36th annual ACM/IEEE design automation conference. new york, ny, usa: Acms. ACM Transactions on Design Automation, page 336, [6] N. Kappiah and D. Lowenthal. Just in time dynamic voltage scaling: Exploiting inter-node slack to save energy in mpi programs. SC 05: Proceedings of the 2005 ACM/IEEE conference on Supercomputing, page 166, November [7] E. Harris and M. Sri-Jayantha. Proceedings of the ieee. Computer., 83(4):636, April 1995.

Android Power Panagement

Android Power Panagement Michael B Motlhabi University of the Western Cape Computer Science Department Modderdam Road Bellville 7535 diablonuva@gmail.com ABSTRACT Saving battery for mobile devices has