University of South Australia

1. University of South Australia Distributed Reconfiguration Avishek Chakraborty, David Kearney, Mark Jasiunas

2. Outline • Motivation • Background • Our approach • Experiment • Conclusion

3. Motivation • UAVs • Limited power • complex signal / image processing applications • FPGAs • Swarm of UAVs • Constant surveillance – 52 hrs* • Cooperative applications: tracking, geo-referencing, bush fire monitoring • Can we do distributed computing with multiple FPGAs? • Migrating applications – dying UAV • Larger application – distribute it in the Swarm

4. Motivation • Mobility of Reconfigurable Applications • If one UAV fails • Any other king of internal fault • Can the state of a FPGA be migrated during runtime? • New App – lack of computational resources • Distribute over a network of FPGAs UAV – 1 (FPGA) New App UAV – 2 (FPGA)

5. Background App • Hardware modules • Independent • Reusable • Third party • Dynamic Reconfiguration • Slot based • ReconfigME • Adaptive applications • Swapping of modules during runtime • Detection / Tracking Netlist ReconfigME

6. Background ReconfigME • ReconfigME • A preemptive framework • A proxy based connection between SW and HW running on the FPGA board • Built to support streaming applications but application developers had to do the check pointing tasks • Currently there are quite a few number of frameworks that supports slot / tile based reconfiguration

7. Application Development • 1 – D and 2 – D reconfigurable framework exists • Runtime placement and routing • Not in the application development level • Application development is difficult • Need to have core hardware knowledge • Even when third party modules are available; developers need to worry about state saving • Inter module communication • More complicated with multiple FPGAs • Need a higher level simple model

8. Kahn Process Network - KPN • Process Networks • Communicates via infinite FIFOs • Writing channel is unblocking but reading is blocking • Benefits • Deterministic • Concurrency can be implemented safely • Inherently distributed in nature • Distributed memory • Suits with module based design • Applications can be easily represented as KPN nodes

9. Kahn Process Network - KPN Capturing State of a distributed application • KPN buffers as registers • Application states are stored in registers • If the buffers are saved then application can be preempted restarted again from the same position • Hence the whole application can be migrated to another FPGA • A high-level framework is needed • Storing / restoring of buffers • Connection between the modules • To use the modules in a plug and play fashion a c b d

10. Kahn Process Network - KPN Buffer Limits • Implementation KPN buffers cannot be infinite • Though some have proposed virtually infinite buffers • The above is directed acyclic graph that may experience deadlock (Thomas M. Parks 1987) • Such constructs can be avoided • In KahnME buffering is done in software but this can be done in HW as well

11. Agent-based KPN nodes AGENT • The KPN nodes as Agents • The nodes are autonomous • Migrates to the most suitable platform • A solution for distributed mapping • Agent encapsulates the KPN node as well as the input buffer • Making them mobile with the state • Migrate from one FPGA to another KPN node Buffer State-less State-full

12. Agent-based KPN nodes • Rule based Agents • Conditions for migration • The rule engine runs in a separate thread • Rules are written in a XML file • Consists of HW and SW part • The SW part consists of the API to connect to the FPGA and the Migration Control Thread • HW part is the module to be placed on the FPGA Events States Modules Rules Reactions Processing Thread Migration Control Thread Agent ReconfigME API Platform

13. Agent-based KPN nodes • An agent nodes can be classified as: • Source, Sink, and Process • Source / Sink virtualizes the underlying hardware, like drivers • Basic elements of any application • Subtle issues: migration of source and sinks • Can be migrated! but not physically • The agent will look for a similar source/sink in the swarm • What if the platform along with source / sink node is dies ? • Failure detections Source Process Sink

14. Overall Model KahnME FPGA FPGA FPGA FPGA ReconfigME ReconfigME ReconfigME ReconfigME

15. Tracking Experiment • Blue – B tracking experiment • Two Stationary UAV platforms and another Ground-Station • Each UAV platforms having Vertex 1000E FPGA (I know very slow ) • The tracking application searches for a Blue-B • Blue-B Tracker • The application is launched in the Ground-Station • it soon starts searching for appropriate platform • Once the Blue-B is found the agent will migrate to another platform if lost again; we did this by manually moving the camera

16. Tracking Experiment The three platforms

17. Tracking Experiment Results • Migration Issues • The migrating agent’s size was 360kB. • Size of the sates 1500 bytes • Rest was of the Blue-B template !! (should have saved it locally but not realistic) • The migrating module consisted of 18.2 kB SW and 492 kB HW (EDIF) • Hence any typical agent will need around 1.5 kB to 672 kB of data during the migration • More Improvements • By compressing the data • In practical situation migrations will be less • Newer board

18. Conclusion • This work represents a first try to run application in a geographically distributed network of FPGAS – Distributed Reconfiguration • We have argued that there is a need to standardized state saving techniques to built frameworks for DPR – reusable modules • We have proposed that KPN buffers can be treated as registers holding states • We have proposed to treat KPN nodes as autonomous agents to solve the problem of distributed reconfiguration