Embed Size (px)
Citation preview
6/17/2002 1 Philip LevisUC Berkeley
Maté: A Tiny Virtual Machine
Viral Programs with a Certain Cosmopolitan Charm
6/17/2002 2 Philip LevisUC Berkeley
Maté
• Motivation• Overview• Architecture, Instructions• Viral code• Evaluation• Bombadillo• Conclusion
6/17/2002 3 Philip LevisUC Berkeley
Motivation
• TinyOS programming complex• Application flexibility needed• Binary reprogramming takes ~2 minutes– significant energy cost– can lose motes
6/17/2002 4 Philip LevisUC Berkeley
Maté Overview
• TinyOS component• 7286 bytes code, 603 bytes RAM• Three concurrent execution contexts• Stack-based bytecode interpreter• Code broken into 24 instruction capsules• Self-forwarding code• Rapid reprogramming• Message receive and send contexts
6/17/2002 5 Philip LevisUC Berkeley
Maté Overview, Continued
• Three execution contexts– Clock, Receive, Send
• Seven code capsules– Clock, Receive, Send, Subroutines 0-3
• One word heap– gets/sets instructions
• Two-stack architecture– Operand stack, return address stack
6/17/2002 6 Philip LevisUC Berkeley
Maté Architecture
0 1 2 3
Subroutines
Clo
ck
Sen
d
Receive
Events
gets/sets
Co
de
OperandStack
ReturnStack
Maté
PC MateContext
6/17/2002 7 Philip LevisUC Berkeley
Maté Instructions
0 1 2 3
Subroutines
Clo
ck
Sen
d
Receive
Events
gets/sets
Co
de
OperandStack
ReturnStack
Maté
PC MateContext
6/17/2002 8 Philip LevisUC Berkeley
Maté Instructions
• Two-stack architecture• One byte per instruction• Three classes: basic, s-type, x-type– basic: data, arithmetic, communication, sensing– s-type: used in send/receive contexts– x-type: embedded operands
basic 00iiiiii i = instruction
s-type 01iiixxx x = argument
x-type 1ixxxxxx
6/17/2002 9 Philip LevisUC Berkeley
Code Snippet: cnt_to_leds
gets # Push heap variable on stackpushc 1 # Push 1 on stackadd # Pop twice, add, push resultcopy # Copy top of stacksets # Pop, set heappushc 7 # Push 0x0007 onto stackand # Take bottom 3 bits of valueputled # Pop, set LEDs to bit patternhalt #
6/17/2002 10 Philip LevisUC Berkeley
cnt_to_leds, Binary
gets # 0x1bpushc 1 # 0xc1add # 0x06copy # 0x0bsets # 0x1apushc 7 # 0xc7and # 0x02putled # 0x08halt # 0x00
6/17/2002 11 Philip LevisUC Berkeley
Sending a Message
pushc 1 # Light is sensor 1sense # Push light reading on stackpushm # Push message buffer on stackclear # Clear message bufferadd # Append reading to buffersend # Send message using built-inhalt # ad-hoc routing system
6/17/2002 12 Philip LevisUC Berkeley
Maté Capsules
0 1 2 3
Subroutines
Clo
ck
Sen
d
Receive
Events
gets/sets
Co
de
OperandStack
ReturnStack
Maté
PC MateContext
6/17/2002 13 Philip LevisUC Berkeley
Maté Capsules
• Hold up to 24 instructions• Fit in a single TinyOS AM packet– Installation is atomic
• Four types: send, receive, clock, subroutine• Context-specific: send, receive, clock• Called: subroutines 0-3• Version information
6/17/2002 14 Philip LevisUC Berkeley
Maté Contexts
0 1 2 3
Subroutines
Clo
ck
Sen
d
Receive
Events
gets/sets
Co
de
OperandStack
ReturnStack
Maté
PC MateContext
6/17/2002 15 Philip LevisUC Berkeley
Contexts
• Each context associated with a capsule• Executed in response to event– external: clock, receive– internal: send (in response to sendr)
• Execution model– preemptive: clock– non-preemptive: send, receive
• Every instruction executed as TinyOS task
6/17/2002 16 Philip LevisUC Berkeley
Viral Code
• Every capsule has version information• Maté installs newer capsules it hears on
network• Motes can forward their capsules (local
broadcast)– forw– forwo
6/17/2002 17 Philip LevisUC Berkeley
Forwarding: cnt_to_leds
gets # Push heap variable on stackpushc 1 # Push 1 on stackadd # Pop twice, add, push resultcopy # Copy top of stacksets # Pop, set heappushc 7 # Push 0x0007 onto stackand # Take bottom 3 bits of valueputled # Pop, set LEDs to bit patternforw # Forward capsulehalt #
6/17/2002 18 Philip LevisUC Berkeley
Evaluation
• Code Propagation• Execution Rate• 42 motes: 3x14 grid• 3 hop network– largest cell 30 motes– smallest cell 15 motes
6/17/2002 19 Philip LevisUC Berkeley
Code Propagation
Network Programming Rate
0%
20%
40%
60%
80%
100%
0 20 40 60 80 100 120 140 160 180 200 220 240
Time (seconds)
Per
cen
t P
rog
ram
med
6/17/2002 20 Philip LevisUC Berkeley
Code Propagation, Continued(seconds)
Network: 1/8 Network: 1/4
New Mean Std. Dev. Mean Std. Dev
1/8 23 8 28 15
1/4 10 4 10 4
1/2 7 3 7 2
1/1 8 2 12 5
Network: 1/2 Network: 1/1
New Mean Std. Dev. Mean Std. Dev
1/8 45 24 361 252
1/4 19 10 425 280
1/2 21 10 226 199
1 14 4 400 339
6/17/2002 21 Philip LevisUC Berkeley
Maté Instruction Issue Rate
• ~10,000 instructions per second• Task operations are 1/3 of Maté overhead
6/17/2002 22 Philip LevisUC Berkeley
Energy Consumption
• Compare with binary reprogramming• Maté imposes a CPU overhead• Maté provides a reprogramming time savings• Energy tradeoff
6/17/2002 23 Philip LevisUC Berkeley
Case Study: GDI
• Great Duck Island application• Simple sense and send loop• Runs every 8 seconds – low duty cycle• 19 Maté instructions, 8K binary code• Energy tradeoff: if you run GDI application
for less than 6 days, Maté saves energy
6/17/2002 24 Philip LevisUC Berkeley
Future Work
• Execution model• Programming language: motlle• Concurrency• Code propagation• Bombadillo: application specific virtual
machines
6/17/2002 25 Philip LevisUC Berkeley
Conclusions
• Spectrum of reprogramming emerges– Hardware– Native code– Bytecode interpreter
• VM can provide user-land guarantees• Will be available in next TinyOS release
6/17/2002 26 Philip LevisUC Berkeley
Questions
