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Octet: Capturing and Controlling Cross-Thread Dependences Efficiently

Michael Bond Milind Kulkarni Man Cao Minjia Zhang Meisam Fathi Salmi Swarnendu Biswas Aritra Sengupta Jipeng Huang. Purdue. Octet: Capturing and Controlling Cross-Thread Dependences Efficiently. Ohio State. Parallel programming is mainstream. Shared memory with locks Challenge:

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Octet: Capturing and Controlling Cross-Thread Dependences Efficiently

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  1. Michael Bond MilindKulkarni Man Cao Minjia Zhang MeisamFathiSalmi SwarnenduBiswas AritraSengupta Jipeng Huang • Purdue Octet: Capturing and Controlling Cross-Thread Dependences Efficiently • Ohio State

  2. Parallel programming is mainstream Sharedmemory with locks Challenge: performance & correctness

  3. Need practical runtime support Help express parallelism better Eliminate concurrency errors Diagnose production bugs Deal with nondeterminism

  4. Need practical runtime support • Transactional memory • DRF/SC enforcement • Deterministic execution • Atomicity checking • Data race detection • Record & replay

  5. Need practical runtime support • Atomicity checking • Data race detection • Record & replay • Transactional memory • DRF/SC enforcement • Deterministic execution • Track dependences • Control dependences o.f = … … = o.f

  6. Need practical runtime support • Atomicity checking • Data race detection • Record & replay • Transactional memory • DRF/SC enforcement • Deterministic execution • Track dependences • Control dependences o.f = … … = o.f

  7. Need practical runtime support • Atomicity checking • Data race detection • Record & replay • Transactional memory • DRF/SC enforcement • Deterministic execution • Track dependences • Control dependences o.f = … … = o.f • Commodity (software-only) approaches • slow programs by several times

  8. Need practical runtime support • Atomicity checking • Data race detection • Record & replay • Transactional memory • DRF/SC enforcement • Deterministic execution • Track dependences • Control dependences check o.f = … check … = o.f • Commodity (software-only) approaches • slow programs by several times

  9. Need practical runtime support • Atomicity checking • Data race detection • Record & replay • Transactional memory • DRF/SC enforcement • Deterministic execution • Track dependences • Control dependences check o.f = … check … = o.f Any access could race add synchronization at every access

  10. Octet • Framework for runtimesupport • HB edges  all dependences • Atomicity of analysis & access • Concurrency control mechanism • Synchronization  cross-thread dependence •  Qualitative performance improvement

  11. Octet • Framework for runtimesupport • HB edges  all dependences • Atomicity of analysis & access • Concurrency control mechanism • Synchronization  cross-thread dependence •  Qualitative performance improvement Proofs!

  12. Octet tracks ownership • Each object’s stateЄ { WrExT, RdExT, RdShc }

  13. o’s state = WrExT1 T1 T2 write check wro.f Time

  14. o’s state = WrExT1 T1 T2 write check read check wro.f Time

  15. o’s state = WrExT1 T1 T2 write check read check wro.f Time

  16. o’s state = WrExT1 T1 T2 write check read check wro.f Time safe point

  17. o’s state = WrExT1 T1 T2 write check read check wro.f Implicit safe point Time safe point

  18. o’s state = WrExT1 T1 T2 write check read check wro.f Time safe point

  19. o’s state = RdExT2 T1 T2 write check read check wro.f Time safe point

  20. o’s state = RdExT2 T1 T2 write check read check wro.f Time safe point rdo.f

  21. o’s state = RdExT2 T1 T2 T3 T4 write check wro.f read check safe point rdo.f

  22. o’s state = RdExT2 T1 T2 T3 T4 write check wro.f read check safe point rdo.f read check

  23. o’s state = RdShc T1 T2 T3 T4 write check wro.f read check safe point rdo.f read check rdo.f

  24. o’s state = RdShc T1 T2 T3 T4 write check wro.f read check safe point rdo.f read check read check rdo.f

  25. o’s state = RdShc T1 T2 T3 T4 write check wro.f read check safe point rdo.f read check read check rdo.f rdo.f

  26. o’s state = RdShc T1 T2 T3 T4 Sharing detection [von Praun & Gross ’01] Comparison in our paper Distributed shared memory Shasta [Scales et al. ’96] Biased locking [Kawachiya et al. ’02] [Russell & Detlefs ’06] [Hindman & Grossman ’06] write check wro.f read check safe point rdo.f read check read check rdo.f rdo.f

  27. Practical runtime support • Atomicity checking • Data race detection • Record & replay • Transactional memory • DRF/SC enforcement • Deterministic execution • Track dependences • Control dependences Framework for runtime support Concurrency control mechanism Octet

  28. Dependence recorder records happens-before edges T1 T2 T3 T4 write check wro.f read check safe point rdo.f read check read check rdo.f rdo.f

  29. Implementation in Jikes RVM • Publicly available • http://jikesrvm.org/Research+Archive Parallel programs DaCapo Benchmarks 2006& 2009 SPEC JBB 2000& 2005 • Parallel platform • 32cores (AMD Opteron 6272)

  30. Octet helps enable practical runtime support for reliable, scalable concurrency • Framework for runtime support • HB edges  all dependences • Atomicity of analysis & access • Concurrency control mechanism • Synchronization  cross-thread dependence • Qualitative performance improvement

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