Apprehending Joule Thieves With Cinder

Transcription

1 Apprehending Joule Thieves With Cinder Stephen M. Rumble, Ryan Stutsman, Philip Levis, David Mazières Stanford University Nickolai Zeldovich MIT 1

2 Handheld Linux 2

3 Desktop Resource Management If it's slow add more resources 3

4 The State of Mobile Devices Complex Running full UNIX stacks Multiprogrammed Software from many sources Hard to trace resource consumption to individual tasks Users care about Energy Network 4

5 The Future of Mobile Devices Need new OS mechanisms Make resource accounting a first class OS primitive This talk: energy Same mechanism applies to networking, which is easier Cinder OS Simple kernel Easy to reason about Familiar UNIX userland 5

6 Cinder Goals Energy as a first class resource Track it Ration it Delegate it In terms the user understands Talk time/standby time rationing Phone calls (total talk time, 911) Games & Widgets folder E mail (composing versus polling) 6

7 Capacitors First class abstraction Can be named and manipulated Protected by permissions All threads run in the context of one or more Track and ration resources for all actions CPU usage Flash writes Network transmissions 7

8 Capacitors maps 8

9 Capacitors Input rate Throttles consumption 1 W maps 9

10 Capacitors Input rate Throttles consumption 1 W Energy storage Allows for burstiness maps 10

11 Capacitors Input rate Throttles consumption 1 W Stored energy Allows for burstiness Half life Acts as a ceiling Prevents hoarding/starvation maps 11

12 Capacitors Input rate Throttles consumption 1 W Stored energy Allows for burstiness Half life 1 W Acts as a ceiling Prevents hoarding/starvation Form a hierarchy maps 12

13 Hierarchy Allows composition of policies Actions debited upward To the battery Block on any empty ancestor Can't perform actions Effectively rate limited maps 13

14 Hierarchy Allows composition of policies Actions debited upward To the battery Block on any empty ancestor Can't perform actions Effectively rate limited maps 14

15 Hierarchy Allows composition of policies Actions debited upward To the battery Block on any empty ancestor X Can't perform actions Effectively rate limited maps 15

16 Hierarchy Allows composition of policies Actions debited upward To the battery Block on any empty ancestor Can't perform actions maps Effectively rate limited 16

17 Hierarchy Allows composition of policies Actions debited upward To the battery Block on any empty ancestor Can't perform actions maps Effectively rate limited 17

18 Hierarchy Allows composition of policies Actions debited upward To the battery Block on any empty ancestor Can't perform actions maps Effectively rate limited 18

19 Throttle Games 20 KJ 1 W 0 J spacewar wumpus rogue 19

20 Downloaded Apps Include resource declarations Background / Foreground Hold them to it 1 MB/mo ($.40) about 3 bps 24 hrs active life about 250 mw 20 KJ 250 mw 0 J 200 MB 3 bps 0 B ifoo 20

21 Composition 20 KJ 1 W 250 mw 0 J 0 J spacewar wumpus rogue ifoo 21

22 Limits on Background Apps User's expectations Driven from interaction Not visible not using energy Foreground Capacitor 20 KJ 250 mw 1 W Increased responsiveness/fidelity Matches user's expectations Driven from specification for downloaded apps ifoo 22

23 Limits on Background Apps User's expectations Driven from interaction Not visible not using energy Foreground Capacitor 20 KJ 250 mw 1 W Increased responsiveness/fidelity Matches user's expectations Driven from specification for downloaded apps ifoo 23

24 Capacitors Fine grained Tracking Rationing Limits Reservations Delegation Composable Can represent Users Applications Classes of Apps Vendors Web application Origins Easily expresses real world policies 24

25 Initial Results OS running on the HTC Dream AKA T Mobile G1 with Google Keyboard, Display, Serial port Incoming and outgoing phone calls work! No audio Text messaging works GPS works for 45 seconds Also runs on x86_64 desktops/laptops 25

26 Initial Results Capacitors implemented All threads are accounted for using capacitors Only accounts for the CPU 26

27 Remaining Work Create a rich energy model for a device Hopefully the HTC Dream Craft interesting policies Validate the approach Experiment with user involvement Allow the user to specify policies easily 27

28 Q&A 28

29 Example 29

30 Example 30

31 Permissions Ownership allows a thread to Change the capacitor's parameters Grant other threads Ownership Consumption allows a thread to Use energy of the capacitor Read energy levels of the capacitor Attach child capacitors Grant other threads Consumption 31

32 Current Mechanisms Users Disk quotas No delegation Processes nice Priorities Can't reason about setrlimit Kill switch Child processes inherit same limits Neither address energy or networking 32

33 State of the art accounting Profile device state consumption Statically or dynamically Account to tasks Bill for device state changes Difficulties Ambiguity Lack of fine grained sensors Prior control systems limited 33

34 Subdivision gui shell maps render route gps sense 34

35 Cgroups Cinder Energy Application controlled Linux Cgroups No energy yet Pluggable Large kernel High baseline 35

36 setrlimit Capacitors Energy Network Limits Blocks on violation Reservations For use in the general case setrlimit No energy No network Kill limits Sends signal or aborts No Reservations Intended for runaways 36

37 ECOsystem/Currentcy Cinder Hierarchical Network ECOsystem Task Containers Energy specific 37

38 Over committing Contention for resources First come first served 10 W 6 W 6 W 38

39 Reservations No Over commiting Act as a reservation 10 W Guaranteed and set aside Works As a rate As a quantity 6 W 4 W 39

40 Reservations No Over commiting 12 J Act as a reservation Guaranteed and set aside Works 10 J As a rate As a quantity 6 J 4 J 40

41 Guarantee a 5 minute 911 call 20 KJ 0 W 250 J

42 Throttle Games 20 KJ 1 W 0 J spacewar wumpus rogue 42

43 Composition 20 KJ 0 W 1 W 250 J 0 J 911 spacewar wumpus rogue 43

44 Amortizing GPS Costs GPSd maps 44

45 Amortizing GPS Costs GPSd maps 45

46 Amortizing GPS Costs GPSd maps 46

47 Amortizing GPS Costs GPSd maps 47

48 Amortizing GPS Costs GPSd loc share 48

49 Amortizing GPS Costs GPSd loc share 49

50 Amortizing GPS Costs GPSd loc share 50

51 Amortizing GPS Costs GPSd loc share 51

52 Amortizing GPS Costs GPSd loc share 52