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Deadlock Detection for Distributed Process Networks

Deadlock Detection for Distributed Process Networks. Alex Olson Embedded Software Spring 2004. Problem Statement. Implement deadlock detection in a distributed process network (DPN) Deadlock detection required for PN scheduling algorithms Deadlock not statically predictable

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Deadlock Detection for Distributed Process Networks

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  1. Deadlock Detection for Distributed Process Networks Alex Olson Embedded Software Spring 2004

  2. Problem Statement • Implement deadlock detection in a distributed process network (DPN) • Deadlock detection required for PN scheduling algorithms • Deadlock not statically predictable • DPN allows for high performance computations • Distributed Process Network • Variable channel latency • Limited bandwidth • No central server

  3. Goals • Achieve high-performance • Deadlock detection should have minimal impact on system performance, resource usage • Deadlock detection should support future addition of dynamic process migration.

  4. Implementation • Distributed Computational Process Network (Allen00) • Zero copy queues • C++, POSIX Threads • Transmit and receive queues • TCP socket for communication • Simple Deadlock Detection Algorithm

  5. Deadlock Detection • Mitchell & Merritt’s algorithm (Mitchell84) • Single-resource model • Detects “local” and “global” deadlocks • Each Process has two labels • Each label is (count, pid) • Guarantees only one process detects deadlock • Send tokens and control information on same socket, make use of FIFO guarantee • No synchronization mechanism required

  6. 1,1 5,5 4,4 3,3 1,1 5,5 4,4 3,3 Mitchell-Merritt Example pub priv

  7. 4,1 5,5 4,4 3,3 4,1 5,5 4,4 3,3 Mitchell-Merritt Example BLOCK pub priv

  8. 4,1 6,5 4,4 3,3 4,1 6,5 4,4 3,3 Mitchell-Merritt Example BLOCK pub priv

  9. 4,1 6,5 4,4 7,3 4,1 6,5 4,4 7,3 Mitchell-Merritt Example BLOCK pub priv

  10. 7,3 6,5 4,4 7,3 4,1 6,5 4,4 7,3 Mitchell-Merritt Example Transmit pub priv

  11. 7,3 7,3 4,4 7,3 4,1 6,5 4,4 7,3 Mitchell-Merritt Example Transmit pub priv

  12. 7,3 7,3 4,4 7,3 4,1 6,5 4,4 7,3 Mitchell-Merritt Example DEADLOCK pub priv

  13. Interface • Processes inherit methods from a “Process” class and implement the following: • void Init() • void Step() • int GetPID()

  14. Performance • Up to 2 Million 1-Byte tokens per second • 120 Mbytes/sec (1kb tokens) • Verified deadlock detection for a a variety of cases

  15. Performance Statistics Token Rate

  16. Performance Statistics Data Rate

  17. Conclusion • Deadlock detection in DPNs can be fairly simple • Method can be applied to regular PNs • DPNs capable of high performance • Future Work • Process Migration • Load Balancing

  18. References

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